Laser ignition system based diagnostics

ABSTRACT

Methods and systems are provided for using an engine laser ignition system to perform a visual inspection of an engine and diagnose various cylinder components and conditions based on engine positional measurements. Laser pulses may be emitted at a lower power level during an intake and/or exhaust stroke to illuminate a cylinder interior while a photodetector captures images of the cylinder interior. Additionally, laser pulses may be emitted at a higher power level to initiate cylinder combustion while the photodetector captures images of the cylinder interior using the light generated during cylinder combustion.

FIELD

The present application relates to methods and systems for diagnosing anengine using components of a laser ignition system.

BACKGROUND AND SUMMARY

Engine system components (such as cylinders, valves, pistons, injectors,etc.) may be intermittently diagnosed for damage incurred during engineoperation. The components may also be diagnosed to identify degradedfunctionality (e.g., incorrect flow, leakage, etc.).

Diagnostics may involve visually inspecting the components for scoringdamage, such as by removing a spark plug and obtaining a bore scope toview inside the cylinder. In another approach, described by Yalin et alin US 2006/0037572, light from a cylinder spark event and/or combustionflame is used to diagnose for the presence of build-up and contaminantsin the cylinder.

The inventors herein have recognized that the above discussed approachescan add extensive time, cost, and complexity to the diagnostics. Inparticular, most of the above approaches require a skilled technician,complex diagnostic tools, specialized laboratory facilities, and timeconsuming engine teardown. In view of these issues, the inventors haverealized that in engine systems configured with laser ignitioncapabilities, components of the laser ignition system can beadvantageously used to diagnose various engine system components. In oneexample, the engine may be diagnosed by a method comprising: initiatingcylinder combustion by operating a laser ignition device; generating anin-cylinder image after operating the laser ignition device using lightgenerated via the cylinder combustion; and displaying the generatedimage to an operator (e.g., a service technician) on a vehicle displaydevice. The operator may then indicate degradation of a cylindercomponent (e.g., piston head, photodetector lens, etc.) or a cylindercombustion characteristic (e.g., flame propagation, flame initiation,etc.) based on the displayed image. In this way, engine cylinderdiagnostics can be expedited and simplified without necessitating enginedisassembly.

For example, the optics of the laser ignition system can be used todiagnose the cylinder during a combustion event. In particular, highpower light pulses may be emitted by the laser ignition device into thecylinder (e.g., during a compression stroke) to initiate cylindercombustion. In-cylinder images may then be captured by a photodetectionsystem coupled to the head of the cylinder using light generated fromthe cylinder combustion event. The photodetection system may include acamera (such as a CCD camera) and a lens (such as a fish-eye lens), fordetecting the light pulses. In one example, the light pulses may beemitted in the infra-red (IR) spectrum by the laser ignition device, anddetected in the IR spectrum by the camera. Images of a condition of theinterior of the cylinder during the combustion may then be generatedbased on the detected pulses. The images may be indicative of, forexample, a condition of the piston head, flame propagation pattern,flame initiation location, flame initiation pattern, timing ofcombustion peak pressure, etc., and may be used to infer degradation.The images may be transmitted (e.g., wirelessly) within the enginesystem and displayed to a service provider (e.g., mechanic or vehicleoperator) on a display of a vehicle center-console. In addition, areference image of the cylinder component/condition being diagnosed maybe retrieved from the controller's memory and displayed to the mechanicfor comparative analysis.

For example, when the image generated is indicative of a piston headcondition, the reference image displayed may be indicative of anexpected piston head condition. A discrepancy between the images maythen be used to diagnose the piston head (e.g., identify piston headmelting). As another example, when the image generated is indicative ofa flame initiation location, the reference image displayed may beindicative of an expected location of flame initiation. A discrepancybetween the images may then be used to diagnose the photodetectionsystem's converging lens. Optionally, if the engine is coupled in ahybrid electric vehicle, an electric motor may be operated during engineoperation to maintain engine speed-load conditions at a referencespeed-load while the in-cylinder images are generated. If the mechanicdetermines that the generated image is sufficiently different from thereference image, the mechanic may determine that there is componentdegradation and may indicate the same to the controller via the displaydevice. Accordingly, a diagnostic code may be set on the engine'scontroller.

In this way, it may be possible to take advantage of a laser ignitionsystem to reduce the time and cost associated with the visual inspectionof an engine, without reducing the accuracy of the inspection. Bycomparing cylinder images gathered by a photodetector followingcombustion in a cylinder, various cylinder components and conditions canbe diagnosed. The diagnostic images generated can be displayed to amechanic, along with reference images for comparison, so that themechanic can identify cylinder component degradation. By using hardwarealready available in an engine configured with a laser ignition system,the need for costly, labor intensive, and time-consuming visualinspections can be reduced. Overall, engine inspection can be simplifiedwithout reducing inspection accuracy.

It should be understood that the summary above is provided to introducein simplified form a selection of concepts that are further described inthe detailed description. It is not meant to identify key or essentialfeatures of the claimed subject matter, the scope of which is defineduniquely by the claims that follow the detailed description.Furthermore, the claimed subject matter is not limited toimplementations that solve any disadvantages noted above or in any partof this disclosure.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows an example combustion chamber of an internal combustionengine coupled in a hybrid vehicle system.

FIG. 2 shows an example of image capture and display using a lasersystem of the engine of FIG. 1.

FIGS. 3 A-B show an example of laser light pulse emission to an enginecylinder.

FIG. 4 shows an example four cylinder engine stopped at a randomposition in its drive cycle.

FIG. 5 shows two operational modes of an engine laser ignition systemused for identifying piston and intake valve positions of a cylinderduring an engine cycle.

FIG. 6 shows a high level flow chart of a method for diagnosingdegradation of one or more cylinder components based on in-cylinderimages generated by a photodetector during an intake stroke.

FIG. 7 shows a high level flow chart of a method for diagnosingdegradation of one or more cylinder components based on in-cylinderimages generated by a photodetector using light from a cylindercombustion event.

FIG. 8 shows a high level flow chart of a method for diagnosingdegradation of one or more engine components based on piston positionand intake valve position measurements performed using an engine laserignition system.

FIGS. 9-10 show an example fuel injector spray pattern diagnosis.

FIGS. 11-13 show example routines for diagnosing degradation of variousengine components, according to the present disclosure.

DETAILED DESCRIPTION

Methods and systems are provided for diagnosing one or more enginecylinder components using a laser ignition system, such as shown inFIG. 1. As shown at FIGS. 2-3, laser light pulse emission at lowerintensities may be used for illuminating the interior of a cylinderwhile a photodetector captures in-cylinder images. Laser light pulseemission at higher intensities may also be used for initiatingcombustion while the light generated during combustion is used by thephotodetector to capture images of the interior of the cylinder. Thegenerated images may be used to diagnose various in-cylinder componentsand cylinder combustion parameters. Further still, cam and pistonposition determination may be accurately performed using the laser lightpulse emission, as shown at FIGS. 4-5 allowing for diagnosis of enginecamshafts and crankshafts, as discussed at FIG. 8. An engine controllermay be configured to perform a control routine, such as the routine ofFIG. 6, to diagnose degradation of one or more cylinder components basedon in-cylinder images generated by a photodetector during an intakestroke using light from laser pulse emission. The controller may alsoperform a control routine, such as the routine of FIG. 7, to diagnosecylinder component degradation based on in-cylinder images generated bya photodetector using light generated during a cylinder combustionevent. Example diagnostic methods for selected engine components areelaborated at FIGS. 9-13.

Turning to FIG. 1, an example hybrid propulsion system 10 is depicted.The hybrid propulsion system may be configured in a passenger on-roadvehicle. Hybrid propulsion system 10 includes an internal combustionengine 20. The engine may be coupled to a transmission (not shown), suchas a manual transmission, automatic transmission, or combinationsthereof. Further, various additional components may be included, such asa torque converter, and/or other gears such as a final drive unit, etc.The hybrid propulsion system also includes an energy conversion device(not shown), which may include a motor, a generator, among others andcombinations thereof. The energy conversion device may be operated toabsorb energy from vehicle motion and/or the engine and convert theabsorbed energy to an energy form suitable for storage at an energystorage device. The energy conversion device may also be operated tosupply an output (power, work, torque, speed, etc.) to engine 20, so asto augment the engine output. It should be appreciated that the energyconversion device may, in some embodiments, include a motor, agenerator, or both a motor and generator, among various other componentsused for providing the appropriate conversion of energy between theenergy storage device and the vehicle drive wheels and/or engine.

Engine 20 may be a multi-cylinder internal combustion engine, onecylinder of which is depicted in detail at FIG. 1. Engine 20 may becontrolled at least partially by a control system including controller12 and by input from a vehicle operator 132 via an input device 130. Inthis example, input device 130 includes an accelerator pedal and a pedalposition sensor 134 for generating a proportional pedal position signalPP.

Combustion cylinder 30 of engine 20 may include combustion cylinderwalls 32 with piston 36 positioned therein. Piston 36 may be coupled tocrankshaft 40 so that reciprocating motion of the piston is translatedinto rotational motion of the crankshaft. Crankshaft 40 may be coupledto at least one drive wheel of propulsion system 10 via an intermediatetransmission system. Combustion cylinder 30 may receive intake air fromintake manifold 45 via intake passage 43 and may exhaust combustiongases via exhaust passage 48. Intake manifold 45 and exhaust passage 48can selectively communicate with combustion cylinder 30 via respectiveintake valve 52 and exhaust valve 54. In some embodiments, combustioncylinder 30 may include two or more intake valves and/or two or moreexhaust valves.

Engine 20 may optionally include cam position sensors 55 and 57.However, in the example shown, intake valve 52 and exhaust valve 54 maybe controlled by cam actuation via respective cam actuation systems 51and 53. Cam actuation systems 51 and 53 may each include one or morecams and may utilize one or more of cam profile switching (CPS),variable cam timing (VCT), variable valve timing (VVT) and/or variablevalve lift (VVL) systems that may be operated by controller 12 to varyvalve operation. To enable detection of cam position, cam actuationsystems 51 and 53 may have toothed wheels. The position of intake valve52 and exhaust valve 54 may be determined by position sensors 55 and 57,respectively. In alternative embodiments, intake valve 52 and/or exhaustvalve 54 may be controlled by electric valve actuation. For example,cylinder 30 may alternatively include an intake valve controlled viaelectric valve actuation and an exhaust valve controlled via camactuation including CPS and/or VCT systems.

Fuel injector 66 is shown coupled directly to combustion cylinder 30 forinjecting fuel directly therein in proportion to the pulse width ofsignal FPW received from controller 12 via electronic driver 68. In thismanner, fuel injector 66 provides what is known as direct injection offuel into combustion cylinder 30. The fuel injector may be mounted onthe side of the combustion cylinder or in the top of the combustioncylinder, for example. Fuel may be delivered to fuel injector 66 by afuel delivery system (not shown) including a fuel tank, a fuel pump, anda fuel rail. In some embodiments, combustion cylinder 30 mayalternatively or additionally include a fuel injector arranged in intakepassage 43 in a configuration that provides what is known as portinjection of fuel into the intake port upstream of combustion cylinder30.

Intake passage 43 may include a charge motion control valve (CMCV) 74and a CMCV plate 72 and may also include a throttle 62 having a throttleplate 64. In this particular example, the position of throttle plate 64may be varied by controller 12 via a signal provided to an electricmotor or actuator included with throttle 62, a configuration that may bereferred to as electronic throttle control (ETC). In this manner,throttle 62 may be operated to vary the intake air provided tocombustion cylinder 30 among other engine combustion cylinders. Intakepassage 43 may include a mass air flow sensor 120 and a manifold airpressure sensor 122 for providing respective signals MAF and MAP tocontroller 12.

Exhaust gas sensor 126 is shown coupled to exhaust passage 48 upstreamof catalytic converter 70. Sensor 126 may be any suitable sensor forproviding an indication of exhaust gas air/fuel ratio such as a linearoxygen sensor or UEGO (universal or wide-range exhaust gas oxygen), atwo-state oxygen sensor or EGO, a HEGO (heated EGO), a NO_(x), HC, or COsensor. The exhaust system may include light-off catalysts and underbodycatalysts, as well as exhaust manifold, upstream and/or downstreamair/fuel ratio sensors. Catalytic converter 70 can include multiplecatalyst bricks, in one example. In another example, multiple emissioncontrol devices, each with multiple bricks, can be used. Catalyticconverter 70 can be a three-way type catalyst in one example.

Controller 12 is shown in FIG. 1 as a microcomputer, includingmicroprocessor unit 102, input/output ports 104, an electronic storagemedium for executable programs and calibration values shown as read-onlymemory chip 106 in this particular example, random access memory 108,keep alive memory 109, and a data bus. The controller 12 may receivevarious signals and information from sensors coupled to engine 20, inaddition to those signals previously discussed, including measurement ofinducted mass air flow (MAF) from mass air flow sensor 120; enginecoolant temperature (ECT) from temperature sensor 112 coupled to coolingsleeve 114; in some examples, a profile ignition pickup signal (PIP)from Hall effect sensor 118 (or other type) coupled to crankshaft 40 maybe optionally included; throttle position (TP) from a throttle positionsensor; and absolute manifold pressure signal, MAP, from sensor 122. TheHall effect sensor 118 may optionally be included in engine 20 becauseit functions in a capacity similar to the engine laser system describedherein. Storage medium read-only memory 106 can be programmed withcomputer readable data representing instructions executable by processor102 for performing the methods described below as well as variationsthereof.

Laser system 92 includes a laser exciter 88 and a laser control unit(LCU) 90. LCU 90 causes laser exciter 88 to generate laser energy. LCU90 may receive operational instructions from controller 12. Laserexciter 88 includes a laser oscillating portion 86 and a lightconverging portion 84. The light converging portion 84 converges laserlight generated by the laser oscillating portion 86 on a laser focalpoint 82 of combustion cylinder 30. In one example, light convergingportion 84 may include one or more lenses.

A photodetector 94 may be located in the top of cylinder 30 as part oflaser system 92 and may receive return pulses from the top surface ofpiston 36. Photodetector 94 may include a camera with a lens. In oneexample, the camera is a charge coupled device (CCD). The CCD camera maybe configured to detect and read laser pulses emitted by LCU 90. In oneexample, when the LCU emits laser pulses in an infra-red frequencyrange, the CCD camera may operate and receive the pulses in theinfra-red frequency range. In such an embodiment, the camera may also bereferred to as an infrared camera. In other embodiments, the camera maybe a full-spectrum CCD camera that is capable of operating in a visualspectrum as well as the infra-red spectrum. The camera may include alens for focusing the detected laser pulses and generating an image ofthe interior of the cylinder. In one example, the lens is a fish-eyelens that creates a wide panoramic or hemispherical image of the insideof the cylinder. After laser emission from LCU 90, the laser sweepswithin the interior region of cylinder 30 at laser focal point 82. Lightenergy that is reflected off of piston 36 may be detected by the camerain photodetector 94. Photodetector 94 may also capture images of theinterior of the cylinder, as elaborated below. Laser system 92 isconfigured to operate in more than one capacity with the timing of eachoperation based on engine position of a four-stroke combustion cycle.For example, laser energy may be utilized for igniting an air/fuelmixture during a power stroke of the engine, including during enginecranking, engine warm-up operation, and warmed-up engine operation. Fuelinjected by fuel injector 66 may form an air/fuel mixture during atleast a portion of an intake stroke, where igniting of the air/fuelmixture with laser energy generated by laser exciter 88 commencescombustion of the otherwise non-combustible air/fuel mixture and drivespiston 36 downward. Furthermore, light generated during the cylindercombustion event may be used by photodetector 94 for capturing images ofan interior of the cylinder. As elaborated at FIG. 9, the generatedimages may then be used to diagnose various in-cylinder components aswell as cylinder combustion parameters.

In a second operating capacity, LCU 90 may deliver low powered pulses tothe cylinder. The low powered pulses may be used to determine piston andvalve position during the four-stroke combustion cycle, as discussed atFIGS. 4-7. The piston position and valve position measurements may thenbe used to diagnose cylinder components such as camshafts andcrankshafts, as discussed at FIG. 10. In addition, upon reactivating anengine from idle-stop conditions, laser energy may be utilized tomonitor the position, velocity, etc. of the engine in order tosynchronize fuel delivery and valve timing. Furthermore, light generatedby the laser light pulse emission at the lower power may be used forcapturing images of an interior of the cylinder before a cylindercombustion event occurs, such as during an intake stroke. The images mayalso be generated during non-combusting conditions, such as whenoperating in specific diagnostic modes. As elaborated at FIG. 8, thegenerated images may then be used to diagnose various in-cylindercomponents.

The images generated at photodetector 94 may be displayed to a mechanicor service technician on a center-console of the vehicle so that theycan perform a visual inspection and identify any cylinder componentdegradation. For example, the laser ignition device, coupled tophotodetector 94, may transmit light pulses into cylinder 30 whilephotodetector 94, including an infrared camera equipped with a fish-eyelens, generates images that are transmitted wirelessly to an enginecontroller and viewed on the display of the vehicle. In some examples,as discussed with reference to FIG. 2, while operating the laserignition device, an operator controlled knob on the center-console canadjust the engine position. These adjustments include turning the engineforwards or backwards from an initial engine position allowing forfurther inspection of the cylinder for an indication of degradation.

LCU 90 may direct laser exciter 88 to focus laser energy at differentlocations depending on operating conditions. For example, the laserenergy may be focused at a first location away from cylinder wall 32within the interior region of cylinder 30 in order to ignite an air/fuelmixture. In one embodiment, the first location may be near top deadcenter (TDC) of a power stroke. Further, LCU 90 may direct laser exciter88 to generate a first plurality of laser pulses directed to the firstlocation, and the first combustion from rest may receive laser energyfrom laser exciter 88 that is greater than laser energy delivered to thefirst location for later combustions. As another example, the laserenergy may be focused at a second location towards the cylinder wallclosest to the intake port of the cylinder in order to diagnose aninjector spray pattern or an intake air flow pattern.

Controller 12 controls LCU 90 and has non-transitory computer readablestorage medium including code to adjust the location of laser energydelivery based on temperature, for example the ECT. Laser energy may bedirected at different locations within cylinder 30. Controller 12 mayalso incorporate additional or alternative sensors for determining theoperational mode of engine 20, including additional temperature sensors,pressure sensors, torque sensors as well as sensors that detect enginerotational speed, air amount and fuel injection quantity. Additionallyor alternatively, LCU 90 may directly communicate with various sensors,such as temperature sensors for detecting the ECT, for determining theoperational mode of engine 20.

As described above, FIG. 1 shows one cylinder of multi-cylinder engine20, and each cylinder may similarly include its own set ofintake/exhaust valves, fuel injector, laser ignition system, etc.

FIG. 2 illustrates an example embodiment 200 of how the laser system 92(of FIG. 1) may emit laser pulses into cylinder 30 so that aphotodetector of the laser system can capture images of the interior ofthe cylinder. The images may be displayed to a vehicle operator toenable visual inspection of the cylinder for damage. As such, componentsalready introduced in FIG. 1 are not re-introduced in FIG. 2.

FIG. 2 shows laser system 92 that includes laser exciter 88,photodetector 94 and LCU 90. LCU 90 causes laser exciter 88 to generatelaser energy. High frequency laser pulses are directed towards variouslocations of the cylinder to scan as much of the cylinder as possible.For example, laser pulses 202 may be directed towards cylinder walls215, interior of cylinder 30, piston top surface 213 and inner surfaceof valves 52 and 54 (that is, the surface facing the cylinder). Byscanning as much of the cylinder as quickly as possible, laser pulse 202acts as a wide beam light source or light bulb enabling photodetector 94(in particular, the CCD camera) to capture images 220 of the interior ofthe cylinder. As such, when operating as a light source for imagecapture during diagnostics, the laser ignition system (or laser device)may be considered to be operating in a projector or illuminator mode,and LCU 90 may receive operational instructions, such as a power mode,from controller 12. When operating in selected diagnostic modes, thelaser system 92 emits a series of low power pulses at high frequency. Incomparison, during ignition, the laser may be pulsed quickly with highenergy intensity to ignite the air/fuel mixture. In one example, duringthe diagnostic mode, the laser may be pulsed at the low energy levelwith a frequency-modulation having a repetitive linear frequency ramp.The low power frequent laser pulses may be emitted in the infra-redspectrum. A photodetection system, which includes a CCD camera operatingin the infra-red spectrum (e.g., an infra-red CCD camera) with afish-eye lens, may be located in the top of the cylinder as part of thelaser and may capture cylinder images 320 using the light energyreflected off the interior of the cylinder. The captured images mayinclude images of the cylinder walls 215, cylinder-facing surface ofintake and exhaust valves 52 and 54, piston top surface 213 and theinterior of cylinder 30. The captured images 220 are transmittedwirelessly by photodetector 94 to controller 12 for viewing on display135 in a vehicle's center-console 140.

Center-console 140 may be included on a vehicle dashboard inside avehicle cabin of the hybrid propulsion system 10 of FIG. 1.Center-console 140 may be a control-bearing surface located in a centralpart of the vehicle cabin, in particular, in the front of the vehiclecabin. Center-console 140 may include various controls, such as knobs138, dials 142, and buttons 136. The various controls may be actuated bya vehicle operator to adjust cabin conditions. The various controls mayinclude, for example, a volume control knob 138 coupled to a musicsystem of the vehicle for adjusting a volume of music in the cabin, atuning button 136 coupled to a radio system of the vehicle for adjustingradio channel selection, and a temperature controlling dial 142 coupledto the vehicle's HVAC system for adjusting cabin heating and coolingtemperatures.

The center-console 140 may also include a display 135. The display maybe a touch-sensitive display that enables the vehicle operator to selectsettings of the vehicle via touch interactions. The display may also beused to display current vehicle settings. In addition, the display maybe used to display a navigation system, such as GPS, phone capabilities,or web applications to be accessed during travel. During conditions whenthe laser ignition device is operated in to capture images fordiagnostic purposes, display 135 is used to depict images of the insideof cylinder 30 which are taken by photodetector 94 coupled to a laserdetection system 92. Specifically, images of the interior of thecylinder taken by a CCD camera of the laser detection system aretransmitted, for example wirelessly, to the engine control system anddisplayed on display 135 to a vehicle operator (e.g., a mechanic). Basedon an operator display preference selected via touch interactions on thedisplay, images of the cylinder interior of any or all the cylinders maybe displayed.

In some examples, during the diagnostic mode, one or more of knobs 138may be activated for engine position control (and deactivated for cabincontrol). For example, when operating in a diagnostic mode, the volumecontrol knob may be activated for engine position control anddeactivated for volume control. Consequently, adjustments to the volumecontrol knob 138 can be used to adjust the engine position from aninitial engine position to assist in the visual inspection of thecylinder. For example, it may be determined that the piston of thecylinder is positioned at or near a top of the cylinder currentlydisplayed on display 135, obstructing a full view of the interior of thecylinder. To improve the view, the vehicle operator may slowly turn thevolume control knob (e.g., clockwise or counterclockwise) which in turnmoves the engine position (e.g., backwards or forwards) such that thepiston is slowly moved towards the bottom of the cylinder viaadjustments to a power-split generator/motor of the engine system. Inembodiments where the engine includes a planetary gear transmission, themotor may hold the outer ring still (which keep the tire wheels still),while the generator (or sun gear), rotates the engine using feedbackfrom either a resolver of the generator position, or using the 60-2crank wheel with hall-effect sensor position system for actual engineposition feedback. This movement of the piston may allow the operator toreceive images representing a more complete view of the interior of thecylinder, and enable him to make a more precise inspection. For example,the improved view may enable the operator to inspect the cylinder wallsfor scoring damage. Further, during the diagnostic mode, the same volumecontrol knob, or an alternate center-console knob, dial, or button maybe activated to enable the image of the cylinder displayed on display135 to be magnified (e.g., zoomed in to or out of).

In one example, the low power light pulses may be emitted in theinfra-red (IR) spectrum by the laser ignition device and the CCD cameramay be configured to operate in the IR spectrum. In alternateembodiments, photodetector 94 may have a full-spectrum CCD camera thatcan be tuned to coordinate with the frequency of the laser; thus, thecamera can operate in IR and other spectrums of light (e.g. daylight orlight bulbs) and has the capability to disable the laser if non-IR lightis detected. Upon observing the images, the vehicle operator (e.g., aservice technician or mechanic) can actively make adjustments to aposition of the piston in order to better view the cylinder. Forexample, during conditions where images 220 indicate that the piston isnear a top of the cylinder (e.g., at TCD), additional adjustments allowfor the engine to be tuned slowly and precisely in order to move thepiston down to the bottom of the cylinder. In the depicted example, whenthe piston is near the top of the cylinder in view, the operator canadjust volume control knob 138 located on the vehicle's center-console140, in order to turn the engine forward or backwards from an initialengine position. If the engine is turned backwards from the initialengine position to move the piston downwards, the controller mayconcurrently open an intake throttle of the engine to reduce expansionof the intake manifold.

FIGS. 3A-B show example operations of the laser system 92. LCU 90 causeslaser exciter 88 to generate a low powered laser pulse shown at 302,which may be directed towards top surface 313 of piston 36. Afteremission, the light energy may be reflected off of the piston anddetected by the photodetector 94. LCU 90 may receive operationalinstructions, such as a power mode, from controller 12. For example,during ignition, the laser pulse used may be pulsed quickly with highenergy intensity to ignite the air/fuel mixture. Conversely, todetermine the engine position, the controller may direct the lasersystem to sweep frequency at low energy intensity to determine pistonposition and identify one or more valve positions. For instance,frequency-modulating a laser with a repetitive linear frequency ramp mayallow a determination of one or more piston positions in an engine. Adetection sensor 94 may be located in the top of the cylinder as part ofthe laser system and may be calibrated to receive return pulse 304reflected from top surface 313 of piston 36.

FIGS. 3A-B illustrate how laser system 92 may emit pulses in thedirection of piston 36 in cylinder 30 described above with reference toFIG. 1. Pulses emitted by laser system 92, e.g., pulse 302 shown in FIG.3A, may be directed toward a top surface 313 of piston 36. Pulse 302 maybe reflected from the top surface of the piston and a return pulse,e.g., pulse 304, may be received by laser system 92, which may be usedto determine a position of piston 36 within cylinder 30.

In some examples, the location of the piston may be determined byfrequency modulation methods using frequency-modulated laser beams witha repetitive linear frequency ramp. Alternatively, phase shift methodsmay be used to determine the distance. By observing the Doppler shift orby comparing sample positions at two different times, piston position,velocity and engine speed information (RPM measurement) may be inferred.The positions of intake valve 352 and/or exhaust valve 354 may also bedetermined using a laser system. When cylinder identity (CID) iscombined with piston location, the position of the engine may bedetermined and used to synchronize fuel delivery and valve timing. Suchpositional states of the engine may be based on piston positions andCIDs determined via lasers.

Controller 12 may further control LCU 90 and include non-transitorycomputer readable storage medium including code to adjust the locationof laser energy delivery based on operating conditions, for examplebased on a position of the piston 36 relative to TDC. Controller 12 mayalso incorporate additional or alternative sensors for determining theoperational mode of engine 20, including additional temperature sensors,pressure sensors, torque sensors as well as sensors that detect enginerotational speed, air amount and fuel injection quantity as describedabove with regard to FIG. 1. Additionally or alternatively, LCU 90 maydirectly communicate with various sensors, such as Hall effect sensors118, whose inclusion is optional, for determining the operational ordiagnostic mode of engine 20.

A laser system may also be utilized to measure cam position by, forinstance, blocking emitted pulses during certain strokes of the enginecycle. For instance, in one embodiment, laser system 92 may be locatednear intake valve 352 so a measurement of piston position within thecylinder is prevented during the intake stroke of the drive cycle.During the intake stroke, valve 352 opens into the chamber and blocksemitted laser pulses from reflecting off of the top surface of thepiston 313. For example, in FIG. 3B, because laser system 92 is placedin close proximity to intake valve 352, when cylinder 30 is in itsintake stroke, valve 352 opens into the chamber and blocks the laserpulse, e.g. laser pulse 306, from reaching the top surface of the piston313. Controller 12 may still be programmed to interpret the signaldetected in order to determine the positions of the cams. For instance,in this example the controller may process a lack of signal received bysensor 94 to indicate that intake valve 352 is in the open position.This information and the geometry of the engine may be further processedby the controller to determine the position of the engine within itsdrive cycle. Although FIG. 3B exemplifies how an emitted pulse may beblocked by intake valve 352, other configurations are possible. Forinstance, the laser system may be located in close proximity to theexhaust valve instead of the intake valve. When placed in this location,pulses emitted may instead be blocked during the exhaust stroke of thedrive cycle. A controller can be calibrated to account for suchdifferences. As described in detail below, controller 12 can processdata collected during the drive cycle to determine engine position.

The difference in time between emission of light pulse 302 and detectionof the reflected light pulse 304 by photodetector 94 can be furthercompared to a time threshold as a means of determining whetherdegradation of the laser device has occurred. For example, in aninternal combustion engine, the combustion chamber may be three to fourinches in length. Based on this estimate, and the speed of light in avacuum (c=3.0×10⁸ m/s), a pulse of light emitted by laser system 92reflected from the top surface of piston 313 may be detected in thepicosecond time range. A time threshold well beyond the expectedpicosecond time range (e.g. 1 nanosecond) may therefore be adopted as areference to indicate degradation of the laser system. For example, apulse emitted by laser system 92 whose detection by sensor 94 takeslonger than 1 nanosecond may indicate a laser system out of alignment.

In some examples, engine system 20 may be included in a vehicledeveloped to perform an idle-stop when idle-stop conditions are met andautomatically restart the engine when restart conditions are met. Suchidle-stop systems may increase fuel savings, reduce exhaust emissions,noise, and the like. In such engines, engine operation may be terminatedat a random position within the drive cycle. Upon commencing the processto reactivate the engine, a laser system may be used to determine thespecific position of the engine. Based on this assessment, a lasersystem may make a determination as to which cylinder is to be fueledfirst in order to begin the engine reactivation process from rest. Invehicles configured to perform idle-stop operations, wherein enginestops and restarts are repeated multiple times during a drive operation,stopping the engine at a desired position may provide for morerepeatable starts, and thus the laser system may be utilized to measureengine position during the shutdown (after deactivation of fuelinjection, spark ignition, etc.) while the engine is spinning down torest, so that motor torque or other drag torque may be variably appliedto the engine, responsive to the measured piston/engine position, inorder to control the engine stopping position to a desired stoppingposition. The piston position information of each cylinder can also beused to estimate crankshaft positions. As elaborated with reference toFIG. 10, based on the relative position of each cylinder's crankshaft,crankshaft degradation (such as due to a twisted or broken crankshaft)can be reliably identified. As shown therein, the interior of the spraypattern provides an indication of the illumination.

In another embodiment, when a vehicle shuts down its engine, eitherbecause the motor is turned off or because the vehicle decides tooperate in electric mode, the cylinders of the engine may eventuallystop in an uncontrolled way with respect to the location of the piston36 in combustion cylinder 30 and the positions of intake valve 352 andexhaust valve 354. For an engine with four or more cylinders, there mayalways be a cylinder located between exhaust valve closing (EVC) andintake valve closing (IVC) when the crankshaft is at rest. FIG. 4 showsas an example an in-line four cylinder engine capable of directlyinjecting fuel into the chamber, stopped at a random position in itsdrive cycle, and how the laser ignition system may provide measurementsthat can be compared among the cylinders to identify engine position. Itwill be appreciated that the example engine position shown in FIG. 4 isexemplary in nature and that other engine positions are possible.

Inset in the figure at 413 is a schematic of an example in-line engineblock 402. Within the block are four individual cylinders wherecylinders 1-4 are labeled 404, 406, 408 and 410 respectively.Cross-sectional views of the cylinders are shown arranged according totheir firing order in an example drive cycle shown at 415. In thisexample, the engine position is such that cylinder 404 is in the exhauststroke of the drive cycle. Exhaust valve 412 is therefore in the openposition and intake valve 414 is closed. Because cylinder 408 fires nextin the cycle, it is in its power stroke and so both exhaust valve 416and intake valve 418 are in the closed position. The piston in cylinder408 is located near BDC. Cylinder 410 is in the compression stroke andso exhaust valve 420 and intake valve 422 are also both in the closedposition. In this example, cylinder 406 fires last and so is in anintake stroke position. Accordingly, exhaust valve 424 is closed whileintake valve 426 is open. The valve position information of eachcylinder can also be used to estimate camshaft positions, as elaboratedat FIG. 10.

Each individual cylinder in an engine may include a laser system coupledthereto as shown in FIG. 1 described above wherein laser system 92 iscoupled to cylinder 30. These laser systems may be used for bothignition in the cylinder and determining cam and piston position withinthe cylinder as described herein. For example, FIG. 4 shows laser system451 coupled to cylinder 404, laser system 453 coupled to cylinder 408,laser system 457 coupled to cylinder 410, and laser system 461 coupledto cylinder 406.

As described above, a laser system may be used to measure valvepositions as well as the position of a piston within a cylinder chamber.For example, in the engine position shown in FIG. 3B, light from lasersystem 92 may be at least partially blocked from reaching the top ofpiston 313 in cylinder 30. Because the amount of light reflected isreduced compared to the amount of light reflected off of the top surfaceof the piston when emitted pulses are not blocked, controller 12 may beprogrammed to account for such differences and use the information todetermine that intake valve 352 is open. Based on the order of valveoperations within the drive cycle, controller 12 further determines thatexhaust valve 354 is closed. Because the example given is based on afour cylinder engine, one of the cylinders will be in an intake strokeat all times. As such, the controller may be programmed to process datafrom all laser systems in order to identify a cylinder in its intakestroke. Based on this determination, and using the geometry of theengine, the position of the engine can be identified using the lasersystems. Alternatively, as will be described in further detail below, acontroller may also be programmed to process a series of measurementsfrom a single laser detector coupled to a cylinder as a means ofidentifying the position of the engine.

The positions of the pistons in a cylinder may be measured relative toany suitable reference points and may use any suitable scaling factors.For example, the position of a cylinder may be measured relative to aTDC position of the cylinder and/or a BDC position of the cylinder. Forexample, FIG. 4 shows line 428 through cross-sections of the cylindersat the TDC position and line 430 through cross-sections of the cylindersin the BDC position. Although a plurality of reference points and scalesmay be possible during a determination of piston position, the examplesshown here are based on the location of the piston within a chamber. Forinstance, a scale based on a measured offset compared to known positionswithin the chamber may be used. In other words, the distance of the topsurface of a piston, shown at 432 in FIG. 4, relative to the TDCposition shown at 428 and BDC position shown at 430 may be used todetermine a relative position of a piston in the cylinder. Forsimplicity, a sample scale calibrated for the distance from the lasersystem to the piston is shown. On this scale, the origin 428 isrepresented as X (with X=0 corresponding to TDC) and the location 430 ofthe piston farthest from the laser system corresponding to the maximumlinear distance traveled by the piston is represented as xmax (withX=xmax corresponding to BDC). For example, in FIG. 4, a distance 471from TDC 428 (which may be taken as the origin) to top surface 432 ofthe piston in cylinder 404 may be substantially the same as a distance432 from TDC 428 to top surface 432 of the piston in cylinder 410. Thedistances 471 and 432 may be less than (relative to TDC 428) thedistances 473 and 477 from TDC 428 to the top surfaces of pistons incylinders 408 and 406, respectively.

The pistons may operate cyclically and so their position within thechamber may be related through a single metric relative to TDC and/orBDC. Generally, this distance, 432 in the figure, may be represented asΔX. A laser system may measure this variable for each piston within itscylinder and then use the information to determine whether furtheraction is to be performed. For instance, a laser system could send asignal to the controller indicating degradation of the crankshaft if thevariable differs by a threshold amount among two or more cylinders. Thevariable X is understood to represent a plurality of metrics that may bemeasured by the system, one example of which is described above. Theexample given is based on the distance measured by the laser system,which may be used to identify the location of the piston within itscylinder.

With reference to FIG. 4, a controller can be programmed to determinethe position of the engine using various methods. For example, thecontroller may be programmed to process a series of data collected froma single laser system, e.g. laser system 461 in cylinder 406, todetermine the position each cylinder's piston, and thereby infer engineposition. An example map of a laser system operating in two differentlow power modes to determine intake valve timing and piston positionwith respect to an engine position during an example engine cycle isshown in FIG. 5 and described below. Alternatively, the controller maybe programmed to process data collected from two or more laser systemsto determine the position of the engine.

FIG. 5 shows a graph 500 of example valve timing and piston positionwith respect to an engine position (crank angle degrees) within the fourstrokes (intake, compression, power and exhaust) of the engine cycle fora four cylinder engine with a firing order of 1-3-4-2. Graph 500 showsintake valve timing and piston position curves along with two exampleposition determination modes of the laser system. A laser system, forexample, laser system 461 coupled to cylinder 406 in FIG. 4, can emit aseries of low-power pulses throughout the engine cycle, but detect twodifferent light signals for valve position estimation and pistonposition estimation within a cylinder. With reference to the exampleshown in FIG. 4, laser system 461 may detect light energy reflected offof the top surface of the piston during the compression, power andexhaust strokes of the drive cycle when the intake valve is closed. Thisdetection mode shown at 506 in FIG. 5 may be a first low power detectionmode (referred to as LD1 in the depicted figure). While the laserdetector senses light energy reflected from the top of the piston inLD1, it may not sense the position of intake valve 426 relative toexhaust valve 424. The controller may use the information generatedduring LD1 to determine the piston position of each cylinder. By thencomparing the relative piston position between cylinders, crankshaftdiagnostics may be performed.

Conversely, when the engine cylinder enters the intake stroke of thedrive cycle, laser detector 461 may detect a reduced signal since itsemission is at least partially blocked by the open intake valve. Thisdetection mode shown at 508 may be a second low power detection mode(referred to as LD2 in the depicted figure). While in LD2, the laserdetector may, for example, sense intake valve position but not theposition of the piston within the cylinder chamber. The controller mayuse the information generated during LD2 to determine the intake valveposition of each cylinder. By then comparing the relative intake valveposition between cylinders, camshaft diagnostics may be performed.Further still, by comparing the crankshaft position and camshaftposition of each cylinder, misalignments between the crankshaft andcamshaft for each cylinder may be identified.

At 502, a valve lift profile is shown for intake valve 426. At thebeginning of the intake stroke, the profile shows that the valve opensand then closes while the piston moves from TDC to BDC. Although a valvelife profile is not shown for exhaust valve, e.g. exhaust valve 424, asimilar profile may be optionally included to show the exhaust valveopens and then closes while the piston moves from BDC to TDC during theexhaust stroke of the engine drive cycle.

At 504, the cyclical nature of the piston is shown for the four strokesof the drive cycle. For example, a piston gradually moves downward fromTDC, bottoming out at BDC by the end of the intake stroke. The pistonthen returns to the top, at TDC, by the end of the compression stroke.The piston then again moves back down, towards BDC, during the powerstroke, returning to its original top position at TDC by the end of theexhaust stroke. As depicted, the map illustrates an engine positionalong the x-axis in crank angle degrees (CAD). For the example curvegiven, a piston position is not shown during the intake stroke toillustrate the signal being reduced due to substantially blocked laserpulses (e.g. more than 90% blocked).

Sample data sets are shown at 510 and 512 to illustrate how differentdata sets may be collected by the laser system. For example, lasersystem 461 may begin collecting data following an engine shutdowncommand as the engine completes its last few cycles before coming torest at position P1. Because P1 is located in an intake stroke, 510shows that the signal collected by the laser detector may be disruptedby the intake valve. As the valve opens, the pulse emitted is at leastpartially blocked, which may result in a substantially reduced signal.Controller 12 may process this signal to identify the open intake valveand use a laser system coupled to another cylinder, e.g. laser system457 coupled to cylinder 410, to measure its piston position. Thegeometry of the engine may then be used to relate all of the variablesas a means of identifying the crankshaft or camshaft position.

Because the action of the drive cycle is cyclical in nature, duringcertain parts of the drive cycle, a second set of data may be collectedwhose initial curve shape may be substantially identical to that shownin 510. To distinguish these two regions from each other and uniquelyidentify the position of the engine, the controller may be programmed toprocess a series of data to determine engine position from curve shape.At 512 a second curve is shown as the piston in cylinder 406 approachesTDC during the compression stroke of the drive cycle. However, becausethe intake valve remains closed during both the compression and powerstrokes, no blockage of the laser signal occurs and a smooth set of datais detected. The controller may be programmed to process such data, anduse the shape of the curve along with the geometry of the engine, toidentify the position of the engine, as well as cylinder crankshafts andcamshafts.

Now turning to FIG. 6, an example method 600 is shown for performing adiagnostic routine to diagnose various in-cylinder components usinglight from a low power laser pulse emitted by an engine laser ignitionsystem, such as the laser system of FIG. 1. The diagnostic mode depictedat FIG. 6 allows for the detection of various components during anintake stroke of a cylinder's combustion cycle.

At 602, it may be confirmed that the engine is on and operating. Forexample, it may be confirmed that the hybrid propulsion system is in anengine mode of operation. If not, the routine moves to 604 to performengine-off diagnostic routines if diagnostic conditions have beenconsidered met. If the engine is on, then at 606, it is determined if afirst diagnostic mode (Mode_1) has been selected. The first diagnosticmode may be selected if specified operating conditions are met. Forexample, engine combusting conditions may be confirmed.

Alternatively, a threshold duration or distance may have elapsed since alast iteration of the first diagnostic mode. When operating in the firstdiagnostic mode, laser pulses may be emitted in a lower power rangeduring an intake stroke of each cylinder. As such, a plurality ofdiagnostic routines, each directed to one or more cylinder components,may be performed while operating in the first diagnostic mode.

If the first diagnostic mode is not selected, the routine moves to 608to determine if a second diagnostic mode (Mode_2) has been selected. Thesecond diagnostic mode may be selected if specified operating conditionsare met. For example, engine combusting conditions may be confirmed.Alternatively, a threshold duration or distance may have elapsed since alast iteration of the second diagnostic mode. As such, a plurality ofdiagnostic routines, each directed to one or more cylinder components,may be performed while operating in the first diagnostic mode. If seconddiagnostic mode conditions are confirmed, the routine moves to FIG. 7 toperform diagnostic routines in the second mode. When operating in thesecond diagnostic mode, laser pulses may be emitted in a higher powerrange during a compression stroke of each cylinder. If neither the firstnor the second diagnostic mode is confirmed, the routine moves to 610where the laser ignition device is operated at a higher power level(above a threshold power level) so as to ignite an air-fuel mixture inthe engine cylinder. Therein, the laser ignition device is operatedduring a compression stroke of the cylinder at the higher power toinitiate fuel combustion in the cylinder.

Returning to 606, if the first diagnostic mode is confirmed, then at612, the routine includes receiving input regarding a selecteddiagnostic routine. As discussed above, various diagnostic routinesdirected to various cylinder components may be performed while operatingin the first diagnostic mode. The controller may receive input from avehicle operator, such as via display 135 of FIG. 2, regarding thecomponent to be diagnosed in the first operating mode. The in-cylindercomponents or conditions diagnosed while operating in the firstdiagnostic mode may include, as non-limiting examples, a cylinder fuelinjector (e.g., to diagnose the injector's spray pattern), cylinderpiston ring (e.g., to diagnose for leakage past the rings), cylindercarbon build-up, poor intake airflow, and the presence of a foreignobject in the cylinder. As such, based on the component to be diagnosed,the number, location, and angle of images captured by a photodetector ofthe laser system, as well as a reference image displayed, may vary.

At 614, after receiving the input, the routine includes operating alaser ignition device (e.g., the laser system of FIG. 1) during anintake stroke of a cylinder at lower power. Operating at lower powerincludes operating at a power lower than a threshold power required forinitiating cylinder combustion. By operating the laser ignition deviceat the lower power during the intake stroke, laser pulses may bedirected into the cylinder to planar sweep the cylinder during theintake stroke. By virtue of the laser rapidly sweeping the interior ofthe cylinder during the intake stroke, the cylinder may be illuminated,as if by a light bulb, and the illumination may be used to captureimages of the interior of the cylinder, thereby allowing an operator toobserve and assess the interior of the cylinder without necessitatingremoval of the components for visual inspection.

In some examples, the planar sweep may be based on the cylindercomponent or condition being diagnosed. For example, when diagnosing aspray pattern of a fuel injector, the planar sweep of the laser ignitiondevice may be oriented into a spray path of the cylinder fuel injector.The laser may be swept in a plane into the path of the injector spray atprecise times after the beginning of the fuel injection during theintake stroke. In comparison, when diagnosing a cylinder piston ring,the planar sweep may be oriented towards the piston surface. The planarsweep used during fuel injector analysis may be a broader sweep than thesweep used for piston analysis. As elaborated below, the determinationof component degradation may be based on input from the operator or maybe an automated determination.

In some embodiments, since the engine is coupled in a hybrid electricvehicle, the routine may include maintaining a reference engine speedand load during the operating of the laser ignition device viaadjustments to an electric motor. This allows the engine speed and loadto be precisely controlled to a predetermined condition for eachdiagnostic test, improving the accuracy and reliability of the results.It also reduces variability in test results due to changes in engineconditions.

At 616, the routine includes receiving in-cylinder images from thephotodetector. Specifically, the photodetector may use the light energyfrom the laser pulse emission to capture images of the interior of thecylinder. The captured images are then transmitted to the displaydevice, for example, wirelessly. In some examples, photodetector camerasettings applied during the different diagnostic routines of diagnosticmode_1 may vary based on the component being diagnosed. The camerasettings adjusted may include, for example, shutter opening duration,aperture settings, time of image capture, etc. As an example, duringfuel injector analysis, the camera shutter may be opened for a longerduration so that several sweeps of the cylinder are captured in a singleimage. In comparison, during cylinder wall carbon build-up analysis, thecamera shutter may be opened for a shorter duration and multiple imagesmay be captured over the several sweeps.

At 618, the routine includes displaying the in-cylinder image(s),captured by the photodetector, to a vehicle operator on the displaydevice. Herein, the vehicle operator may be, for example, a mechanic orservice technician diagnosing the engine. For example, after each planarsweep of the laser, the captured image may be automatically presented tothe service technician for analysis.

Optionally, at 620, the controller may display a reference image of thecomponent or condition being diagnosed to the vehicle operator on thedisplay device. The reference image may be stored in, and retrievedfrom, the controller's memory. Furthermore, the reference image may be areference image previously generated by the photodetector, such asduring predetermined conditions (e.g., on a previous iteration of thegiven diagnostic routine when no degradation was detected). Thereference image may be retrieved based on the input regarding thediagnostic routine previously received at 612. Additionally, thereference image may be selected based on the generated image.Alternatively, the reference image may be retrieved and displayedfollowing operator input received via the display device after displayof the captured image(s) on the display device. As an example, when thecylinder component being diagnosed is a cylinder fuel injector, such asa cylinder port fuel injector, the in-cylinder image generated by thephotodetector may be indicative of a spray pattern of the fuel injector,such as a spray pattern of the port fuel injector. The reference imageretrieved by the controller may be of an expected spray pattern from aproperly functioning fuel injector. An example of such a comparison isdiscussed herein with reference to FIG. 10. Based on differences betweenthe expected pattern and the actual pattern, the operator may be able toindicate fuel injector degradation. Specifically, the comparison of twoimages may provide objective evidence of the need for replacement of thefuel injector.

At 622, the routine includes receiving input from the vehicle operatorregarding a health of the component or condition being diagnosed, theoperator input based on the displayed in-cylinder image and referenceimage. For example, the operator may compare the displayed image withthe reference image, and based on a large discrepancy, the operator mayindicate that component degradation has occurred.

In one example, the cylinder component being diagnosed may be thecylinder piston rings and the in-cylinder image generated may beindicative of a state of the cylinder piston rings. The reference imagedisplayed may include an image of the cylinder piston during an intakestroke. If the in-cylinder image captured by the photodetector duringthe intake stroke is indicative of crankcase vapor condensation at thepiston, the operator may indicate that the cylinder piston rings aredegraded and vapors coming from the crankcase are condensing in thecylinder near the piston.

As another example, the cylinder component being diagnosed may be acylinder combustion chamber and the in-cylinder image may be compared toa reference image to indicate if a foreign object is present (e.g.,bounding around) in the combustion chamber. For detecting the presenceof foreign objects, still and/or video images captured by thephotodetector may be used. The still images may include time lapsedstill images captures over an intake stroke and an exhaust stroke (suchas the exhaust stroke immediately preceding the intake stroke). If videoimages are analyzed, the analysis may include the playback of videoimages captured during the intake stroke and the exhaust stroke. Thevideo images may be played back in slow motion to detect foreign objects(such as a nut, bolt, rag, etc.) that may be bouncing around in thecylinder. The foreign object may have entered the cylinder during priormaintenance operations or engine assembly, such as when the air intakewas assembled. In response to the detection of a foreign object, adiagnostic code may be set to indicate that the object needs to beremoved from the specific cylinder.

As still another example, the images of the interior of the cylindercaptured during the intake stroke may be analyzed to assess carbonbuild-up in the cylinder. Therein, the image of the cylinder wall may bestudied and the reflectivity of the wall may be noted. The reflectivityof the cylinder wall in the captured image may be compared to thereflectivity of the cylinder wall in a reference image of a cleancylinder. As such, a clean cylinder may generate a shiny image with ahigh reflectivity of the cylinder wall. In comparison, a cylinder withsoot build-up may generate a dull or black image with a low reflectivityof the cylinder wall. Thus, based on the images indicating a drop incylinder wall reflectivity, it may be determined that there is excessivecarbon or soot build-up on the cylinder wall. In response to thebuild-up, a diagnostic code may be set to indicate soot build-up. Thecontroller may also direct the engine to run leaner than stoichiometryfor a period of time or direct the laser to burn-off areas withexcessive carbon build-up to address the elevated cylinder soot levels.The controller may also direct the diagnostic to investigate the pistonring integrity by scrutinizing the images from that test.

As such, analysis of images captured during an intake stroke forcylinder wall carbon build-up analysis may be different from analysis ofimages captured during an exhaust stroke for misfire detection. Therein,high reflectivity of the cylinder wall during the exhaust stroke may beindicative of a hot spot which can increase the propensity for misfires.Therefore, in response to high cylinder wall reflectivity observedduring an exhaust stroke, a hot spot with carbon build-up may bedetermined and soot burn off may be requested. In comparison, inresponse to low cylinder wall reflectivity observed during an intakestroke, carbon build-up may be determined and soot burn off may berequested.

In yet another example, elaborated herein with reference to FIG. 11, thecylinder component diagnosed may be an intake valve, wherein thein-cylinder image captured at different times since intake valve openingmay be compared to a reference image to indicate coolant entry orleakage into the cylinder via the intake valve.

If operator input indicative of degradation is received, then at 624, inresponse to the operator input, the routine includes setting adiagnostic code to indicate component degradation. The diagnostic codemay also indicate component replacement or repair is required, asappropriate. If component degradation is not determined by the operator,then at 626, the routine indicates that the diagnosed component orcondition is not degraded and that the component is in good health.

From 624 and 626, the routine moves to 628 wherein it is determined if anew diagnostic routine request has been received. For example, it may bedetermined if conditions for another diagnostic routine that usesillumination from low power laser operation in the intake stroke havebeen met. If yes, the routine returns to 612 to receive input regardingthe diagnostic to be performed and the component or condition to bediagnosed. The routine is then reiterated. The routine of FIG. 6 isreiterated from 612 to 628 to complete all the diagnostic routines thatcan be performed while operating in the first diagnostic mode. Ifconditions for a particular diagnostic routine are not met, or if asufficient number (e.g., all) of the diagnostic routines of Diagnosticmode_1 are completed, routine 600 may end.

While the above routine depicts the need for an operator to analyze thegenerated image(s) and indicate whether component degradation hasoccurred, in alternate embodiments, the analysis may be automated. Forexample, following image capture in the intake stroke, the image may beautomatically displayed on the display device, and a correspondingreference image may also be automatically displayed on the displaydevice. The controller may then compare the images, without requiringoperator input, to provide a pass/fail result of the diagnostic routine.The pass/fail determination may be based on similarity of the images(that is, the generated image and the reference image) via a simpler,less computation-intensive pixel comparison or an advanced, morecomputation-intensive image analysis. In the advanced image analysis,objects within the image may be identified for a more precise evaluationof the component or condition being studied.

It will be further appreciated that while the above routine suggests theuse of the laser system coupled to the engine for diagnostic purposes,in alternate examples, the laser system including the laser exciter, thelenses, and the photodetector, may be configured as a mobile laboratorytool. Therein, the laser system may be configured as a portable toolthat can be coupled to any engine, such as an engine with spark plugs,or an engine that has been removed from a vehicle, and used foranalyzing the engine. As an example, the mobile tool may be placed inthe intake manifold, or intake port, of an engine, to view and analyzethe injector spray pattern (such as the port injector spray pattern) forthe engine. As another example, in the case of engines with spark plugs,the mobile tool may be advantageously used for analyzing spark qualityas well as spark plug fouling. As a further example, a cylinder sparkplug may be removed and the mobile tool may be placed in the position ofthe spark plug for capturing images of an interior of the cylinder andanalyzing other in-cylinder components. As such, the mobile tool mayprovide various advantages over spark-plug based tools. For example, byreplacing the spark plug with a laser, spark plug fouling may not beinduced with prolonged use, as may occur in a laboratory setting. Asanother example, the mobile tool may include its own video display unitand processing for use on vehicles that do not possess the laserdiagnostic interface display.

In one example, a hybrid vehicle system comprises an engine includes acylinder; an electric motor; a display device in a cabin of the vehicle;as well as a laser ignition system coupled to a cylinder head andconfigured to direct light pulses into the cylinder. The engine furtherincludes a photodetection system coupled to the laser ignition systemand the cylinder for generating images of an inside of the cylinderusing the light pulses from the laser ignition system. Thephotodetection system may include, for example, a CCD camera with afish-eye lens. The vehicle system may further include a controller withnon-transitory memory and computer readable instructions for: operatingthe laser ignition system during the intake stroke at a lower powerlevel; displaying an in-cylinder image generated at the photodetectionsystem following the operating to a vehicle operator on the displaydevice; and further displaying a reference image retrieved from thecontroller's memory on the display device, the reference image based onthe generated in-cylinder image. The controller may receive input fromthe vehicle operator via the display device indicative of cylindercomponent degradation and set a diagnostic code based on the receivedinput. The controller may include further instructions for adjusting anoutput of the electric motor when operating the laser ignition system tomaintain a reference engine speed and load while generating thein-cylinder image. The reference engine speed and load may correspond topredetermined conditions for the specific diagnostic routines. Thisallows for better control over the operating conditions under which theimages are captured in relation to those when the reference image wascaptured.

Now turning to FIG. 7, an example method 700 is shown for performing adiagnostic routine to diagnose various in-cylinder components usinglight from a high power laser pulse emitted by an engine laser ignitionsystem, such as the laser system of FIG. 1. The diagnostic mode depictedat FIG. 7 allows for the detection of various components during acylinder combustion event.

At 702, it is determined if a second diagnostic mode (Mode_2) has beenselected. The second diagnostic mode may be selected if specifiedoperating conditions are met. For example, engine combusting conditionsmay be confirmed. Alternatively, a threshold duration or distance mayhave elapsed since a last iteration of the second diagnostic mode. Assuch, a plurality of diagnostic routines, each directed to one or morecylinder components, may be performed while operating in the seconddiagnostic mode.

If the first diagnostic mode is not selected, the routine moves to 608to determine if a second diagnostic mode (Mode_2) has been selected. Thesecond diagnostic mode may be selected if specified operating conditionsare met. For example, engine combusting conditions may be confirmed.Alternatively, a threshold duration or distance may have elapsed since alast iteration of the second diagnostic mode. As such, a plurality ofdiagnostic routines, each directed to one or more cylinder components,may be performed while operating in the first diagnostic mode. If seconddiagnostic mode conditions are not confirmed, at 704, laser ignition maybe disabled. Laser ignition may then remain disabled until cylinderignition is required, or until conditions for a diagnostic routine ofMode_2 are confirmed.

If the second diagnostic mode is confirmed, at 706, the routine includesreceiving input regarding a selected diagnostic routine. As discussedabove, various diagnostic routines directed to various cylindercomponents may be performed while operating in the second diagnosticmode. The controller may receive input from a vehicle operator, such asvia display 135 of FIG. 2, regarding the component to be diagnosed inthe second operating mode. The in-cylinder components or conditionsdiagnosed while operating in the second diagnostic mode may include, asnon-limiting examples, the conditions of a cylinder piston head,alignment of a converging lens of the laser system, cylinder combustionparameters such as flame propagation, flame initiation, as well asair-fuel ratio control. As such, based on the component or conditions tobe diagnosed, the number, location, and angle of images captured by aphotodetector of the laser system, as well as a reference imagedisplayed, may vary.

At 708, after receiving the input, the routine includes initiatingcylinder combustion by operating a laser ignition device (e.g., thelaser system of FIG. 1). This may include operating the laser ignitiondevice at a higher power level, such as at a power level higher than athreshold power required for only illuminating an interior of thecylinder. In addition, the laser ignition device may be operated todirect laser pulses into the cylinder to planar sweep the cylinderduring a compression stroke of the cylinder. For example, the laserpulses may be directed at the center of the cylinder to give a smooth,even, and completion combustion pattern with the entire cylinderstarting from a point or line in the center and moving radially outwardsto the walls, ending at the same instant. In addition, crevice spacesmay get an additional hit. In this way, the light from the ignitionflame may be used for combustion flame analysis. By virtue of the laserrapidly sweeping the interior of the cylinder during the compressionstroke, cylinder combustion may be initiated and the cylinder may beilluminated, as if by a light bulb, using the light generated fromcylinder combustion. The illumination may be used to capture images ofthe interior of the cylinder, thereby allowing an operator to observeand assess the interior of the cylinder without necessitating removal ofthe components for visual inspection. In some examples, as discussedpreviously, the planar sweep may be based on the cylinder component orcondition being diagnosed. As such, since the flame may obscure the viewof the cylinder parts during the combustion, the light bulb effect isprovided only with low energy laser sweeping when the flame is complete

In some embodiments, where the engine is coupled in a hybrid electricvehicle, the routine may include maintaining a reference engine speedand load during the operating of the laser ignition device viaadjustments to an electric motor. This allows the engine speed and loadto be precisely controlled to a predetermined condition for eachdiagnostic test, improving the accuracy and reliability of the results.It also reduces variability in test results due to changes in engineconditions.

At 710, the routine includes receiving in-cylinder images from thephotodetector. Specifically, the photodetector may use the lightgenerated from the cylinder combustion (following laser ignition) tocapture images of the interior of the cylinder. The captured images arethen transmitted to the display device, for example, wirelessly.

At 712, the routine includes displaying the in-cylinder image(s),captured by the photodetector, to a vehicle operator on a vehicledisplay device. Herein, the vehicle operator may be, for example, amechanic or service technician diagnosing the engine. For example, aftereach combustion event, the captured image may be automatically presentedto the service technician for analysis. Alternatively, after everycombustion event, an image of each laser sweep may be sent to theoperator.

Optionally, at 714, the controller may display a reference image of thecomponent or condition being diagnosed to the vehicle operator on thedisplay device. The reference image may be stored in, and retrievedfrom, the controller's memory. The reference image may include areference image previously generated by the photodetector duringpredetermined conditions, such as on a previous iteration of the givendiagnostic routine when no degradation was detected. The reference imagemay be retrieved based on the input regarding the diagnostic routinepreviously received at 706. Additionally, the reference image may beselected based on the generated image. Alternatively, the referenceimage may be retrieved and displayed following operator input receivedvia the display device after display of the captured image(s) on thedisplay device.

As an example, when the cylinder component being diagnosed is a piston,the in-cylinder image generated by the photodetector may be indicativeof a piston head. The reference image retrieved by the controller may beof a functional (that is, undegraded) piston head of similar age. Basedon differences between the reference image and the actual image, theoperator may be able to indicate piston head degradation, such as pistonhead melting. Specifically, the comparison of the two images may provideobjective evidence of the need for replacement of the piston.

At 716, the routine includes receiving input from the vehicle operatorregarding a health of the component or condition being diagnosed, theoperator input based on the displayed in-cylinder image and referenceimage. For example, the operator may compare the displayed image to thereference image, and based on a discrepancy, the operator may indicatethat component degradation has occurred.

In one example, the cylinder combustion parameter being diagnosed may becylinder combustion flame propagation. The captured image displayed mayinclude time lapsed images of the flame front, including images of flameprogression from the center of the cylinder outwards. The images may becaptures at precise times including and following the laser ignitionevent. The reference image displayed may likewise include time lapsedimages of the flame front, as expected, from the center of the cylinderoutwards at the corresponding times in a good known cylinder. If theshape and/or intensity of the flame as it progresses in the capturedimage does not match the expected shape and intensity, as shown in thereference image, degradation of flame propagation may be determined. Forexample, the flame front in the reference image may form a ball-likeshape. If the captured image does not show a flame front with aball-like shape, improper flame propagation may be determined. Asanother example, if the flame front in the captured image has a lowerintensity than the flame front of the reference image, improper flamepropagation may be determined. In response to the indication of flamefront degradation, a diagnostic code may be set. If the remaining laserdiagnostics all pass (that is, no degradation is determined), furtheranalysis of the fuel or compression is required may be indicated.Otherwise, the degraded cylinder component or laser control system isidentified by the remaining diagnostics with a unique diagnostic code.

As another example, the combustion parameter diagnosed may include flameinitiation. This reflects the location where the flame front originates.For example, the generated images may be indicative of a location on thepiston head where the flame front initiated. Since the combustion isinitiated via laser ignition, the location of flame front initiationcorrelates with the location of lens convergences produces laserintensity sufficient to cause combustion in the mixture, or where thelaser may impinge in the cylinder. That is, the captured image isindicative of an orientation of laser pulses output by the laserignition device. The reference image may indicate a location on thepiston head where the flame front is expected to initiate and the laseris expected to hit first. If the captured image indicates that thelocation of flame initiation is askew relative to the expected location(e.g., makes a chord), degradation may be indicated. Specifically,incorrect orientation or aiming of the laser may be indicated. Inresponse to the indication of incorrect orientation, a diagnostic codemay be set to fix the alignment of the laser device.

The generated images of a location on the piston head where the flamefront initiated may also be indicative of a focal point of a lens (suchas a converging lens) coupled to the laser ignition device. Since thelocation of flame front initiation correlates with the location wherethe intensity of laser impingement is highest, assuming the alignment ofthe laser device is correct, the location of flame initiation correlateswith the focal point of the converging lens. Furthermore, the locationwhere the flame front intensity is the highest correlates with the focalpoint of the converging lens, which may be in the precise center of thecylinder volume or on the piston head. If the captured image indicatesthat the location of flame initiation is askew relative to the expectedlocation (e.g., makes a chord), degradation may be indicated.Specifically, incorrect orientation of the lens and incorrect flameinitiation may be indicated. Alternatively, the captured image may beused to calculate a distance from the laser where the spark occurred andflame initiated. If the calculated distance is different from thedistance calculated based on the reference image, incorrect orientationof the lens may be determined. In response to the indication ofincorrect orientation of the lens, a diagnostic code may be set to fixthe alignment of the lens.

It will be appreciated that in some examples, analysis of the locationof flame initiation may require a specific orientation of thephotodetector camera relative to the laser. For example, thephotodetector camera may be lateral to (e.g., on a side or edge of) thelaser rather than aligned on top of the laser. As discussed below, thisconfiguration may be achieved in mobile tool applications of the lasersystem.

As another example, the in-cylinder component being diagnosed may be acylinder piston head. Therein, the scanned image of the piston head maybe compared to a stored reference image of a similarly aged piston headwithout degradation. By comparing the images, a melted piston head maybe detected and piston replacement may be objectively determined by theoperator.

In yet another example, the spectral analysis may be used for combustionair-fuel ratio (AFR) control. Herein, the diagnostic routine may beperformed as a part of various engine on-board diagnostic (OBD)routines. The spectral analysis may be used for AFR control independentof a UEGO sensor-based AFR control. Alternatively, the spectral analysismay be used to supplement or validate the UEGO based AFR control.Therein, the generated in-cylinder image(s) may be indicative of alocation or timing of a stoichiometric point of combustion. As such, atany given time of engine operation, there may be at least one cylinderperforming better (or worse) than all the others. Herein, the capturedimage may be used to indicate Lambda for each cylinder combustion event.The images may be captured and analyzed on every single combustion eventor cylinder. Based on the captured image, cylinder specific preciseair-fuel ratio control may be performed. The stoichiometric point foreach cylinder may be learned and used to trim AFR errors. Specifically,air mass delivery and fuel injection timing may be fine-tuned for eachcylinder. By enabling each cylinder to operate at Lambda more precisely,instead of operating too rich or too lean, overall engine fuel economycan be improved.

If operator input indicative of degradation is received, then at 718, inresponse to the operator input, the routine includes setting adiagnostic code to indicate component or condition degradation. Thediagnostic code may also indicate component replacement or repair isrequired, as appropriate. If component degradation is not determined bythe operator, then at 720, the routine indicates that the diagnosedcomponent or condition is not degraded and that the component is in goodhealth.

From 718 and 720, the routine moves to 722 wherein it is determined if anew diagnostic routine request has been received. For example, it may bedetermined if conditions for another diagnostic routine that usesillumination from high power laser operation during and following theignition event have been met. If yes, the routine returns to 706 toreceive input regarding the diagnostic to be performed and the componentor condition to be diagnosed. The routine is then reiterated. Theroutine of FIG. 7 is reiterated from 706 to 722 to complete all thediagnostic routine that can be performed while operating in the seconddiagnostic mode. If conditions for a particular diagnostic routine arenot met, or if a sufficient number (e.g., all) of the diagnosticroutines of Diagnostic mode_2 are completed, routine 700 may end.

While the above routine depicts the need for an operator to analyze thegenerated image(s) and indicate whether component degradation hasoccurred, in alternate embodiments, the analysis may be automated. Forexample, following image capture, the image may be automaticallydisplayed on the display device, and a corresponding reference image mayalso be automatically displayed on the display device. The controllermay then automatically compare the images, without requiring operatorinput, to provide a pass/fail result of the diagnostic routine. Thepass/fail determination may be based on similarity of the images (thatis, the generated image and the reference image) via a simpler, lesscomputation intensive pixel comparison or an advanced, more computationintensive image analysis. In the advanced image analysis, objects withinthe image may be identified for a more precise evaluation of thecomponent or condition being studied.

It will be further appreciated that while the above routine suggests theuse of the laser system coupled to the engine for diagnostic purposes,in alternate examples, the laser system including the laser exciter, thelenses, and the photodetector, may be configured as a mobile laboratorytool. Therein, the laser system may be configured as a portable toolthat can be coupled to any engine, such as an engine with spark plugs,or an engine that has been removed from a vehicle, and used foranalyzing the engine. As an example, the mobile tool may be placed inthe intake manifold, or intake port, of an engine, to view and analyzeflame front initiation. This may include separating the laser systemcomponents and localizing the laser and the photodetector at differentlocations of the intake port for a given diagnostic routine.

In this way, a method is provided for visual inspection of enginecomponents without requiring engine teardown. The method comprisesoperating a laser ignition device during a compression stroke toinitiate cylinder combustion; transmitting an in-cylinder imagegenerated after operating the laser ignition device to a vehicle displaydevice, the image generated by a photodetector of the cylinder usinglight generated via the cylinder combustion; and based on input receivedfrom an operator, setting a diagnostic code indicating degradation.Herein, the photodetector is coupled to the cylinder, the photodetectorincluding a lens and a camera. The in-cylinder image captured is animage of a cylinder component or combustion parameter. The methodfurther comprises displaying a reference image to the operator on thevehicle display device, the reference image selected based the cylindercomponent or combustion parameter. Indicating degradation includesindicating degradation of the cylinder component or combustion parameterbeing diagnosed. For example, when the in-cylinder image is an image ofcombustion flame initiation, indicating degradation includes indicatingdegradation of the photodetector lens.

In one example, a hybrid vehicle system comprises an engine includes acylinder; an electric motor; a display device in a cabin of the vehicle;a laser ignition system coupled to a cylinder head and configured todirect light pulses into the cylinder; and a photodetection systemcoupled to the laser ignition system and the cylinder for generatingimages of an inside of the cylinder using the light pulses from thelaser ignition system. The vehicle system may include a controller withnon-transitory memory and computer readable instructions for operatingthe laser ignition system during the compression stroke to initiatecylinder combustion; displaying an in-cylinder image generated at thephotodetection system following the operating to a vehicle operator onthe display device; and further displaying a reference image retrievedfrom the controller's memory on the display device, the reference imagebased on the generated in-cylinder image. Operating the ignition deviceduring the compression stroke may include operating the laser ignitionsystem above a threshold power level. The photodetection system may thencapture images of the interior of the cylinder during and following theignition event using light generated by the cylinder combustion. Thecontroller may then indicate cylinder combustion degradation based onoperator input received following the displaying. As an example, thephotodetection system may include a CCD camera with a fish-eye lens.Displaying the images may include wirelessly transmitting images withinthe vehicle system from the photodetection system to the display device.The controller may include further instructions for adjusting an outputof the electric motor when operating the laser ignition system tomaintain a defined engine speed and load while generating thein-cylinder image.

In this way, the routines of FIGS. 6-7 depict a method of using a laserignition system at different power levels and at different times duringa combustion cycle to diagnose various engine components. For example, amethod for an engine is proved that comprises operating a laser ignitiondevice during an intake stroke at a lower power level to generate afirst in-cylinder image; operating the laser ignition device during acompression stroke at a higher power level to generate a secondin-cylinder image; and displaying each of the first and secondin-cylinder image to a vehicle operator on a display device. The methodfurther includes receiving input from the vehicle operator indicative ofdegradation of a first cylinder component based on the first image, andinput indicative of degradation of a second, different cylindercomponent based on the second image. For example, the first cylindercomponent may include one or more of a fuel injector, cylinder intakevalve, and cylinder piston ring, while the second cylinder component mayinclude one or more of a lens and laser of the laser ignition device.

Now turning to FIG. 8, an example method 800 is shown for performing adiagnostic routine to diagnose various in-cylinder components usingillumination based position measurements following low power laser pulseemission by an engine laser ignition system, such as the laser system ofFIG. 1. The diagnostic mode depicted at FIG. 8 allows for the diagnosisof various components based on their absolute or relative positions.

At 802, it may be confirmed that the engine is not combusting (e.g.engine-off). For example, it may be confirmed that the hybrid propulsionsystem is in an electric mode of operation or the engine is in anidle-stop mode. If not, the routine moves to 804 to perform engine-ondiagnostic routines if diagnostic conditions have been considered met,such as the routines discussed at FIGS. 6-7. If the engine is notcombusting, then at 806, it is determined if a third diagnostic mode(Mode_3) has been selected. The third diagnostic mode may be selected ifspecified operating conditions are met. For example, enginenon-combusting conditions may be confirmed. Alternatively, a thresholdduration or distance may have elapsed since a last iteration of thethird diagnostic mode. When operating in the third diagnostic mode,laser pulses may be emitted in a lower power range into eachnon-combusting cylinder. As such, a plurality of diagnostic routines,each directed to one or more cylinder components, may be performed whileoperating in the third diagnostic mode.

If the third diagnostic mode is not selected, the routine moves to 808to disable the laser ignition system. If the third diagnostic mode isconfirmed, then at 810, the routine includes receiving input regarding aselected diagnostic routine. As discussed above, various diagnosticroutines directed to various cylinder components may be performed whileoperating in the third diagnostic mode. The controller may receive inputfrom a vehicle operator, such as via display 135 of FIG. 2, regardingthe component to be diagnosed in the third operating mode. Thein-cylinder components or conditions diagnosed while operating in thethird diagnostic mode may include, as non-limiting examples, a cylindercrankshaft and a cylinder camshaft. In some examples, based on thecomponent to be diagnosed, the number, frequency, orientation, and powerlevel of the laser pulses emitted by the laser system may vary.

At 812, after receiving the input, the routine includes operating alaser ignition device in each cylinder. Specifically, a laser ignitiondevice (e.g., the laser system of FIG. 1) may be operated during anintake stroke of a cylinder at lower power. Additionally or optionally,the laser ignition device may be operated during an exhaust stroke ofeach engine cylinder. Operating at lower power includes operating at apower lower than a threshold power required for initiating cylindercombustion. By operating the laser ignition device at the lower powerduring the intake stroke, laser pulses may be directed into the cylinderto planar sweep the cylinder during the intake stroke. By virtue of thelaser rapidly sweeping the interior of the cylinder during the intakestroke, the cylinder may be illuminated, as if by a light bulb, and theillumination may be used to capture images of the interior of thecylinder, thereby allowing an operator to observe and assess theinterior of the cylinder without necessitating removal of the componentsfor visual inspection.

At 814, the routine includes identifying a piston position in eachcylinder based on the operating of the laser ignition device.Identifying the piston position in each cylinder includes, for eachcylinder, sensing light reflected off a top surface of the piston andestimating the piston position based on a time elapsed between theoperating of the laser ignition device and the sensing of the light. Forexample, the location of the piston may be determined by frequencymodulation methods using frequency-modulated laser beams with arepetitive linear frequency ramp.

At 816, the routine further includes identifying a cylinder valveposition in each cylinder based on the operating of the laser ignitiondevice. In one example, the cylinder valve is an intake valve. In otherexamples, the cylinder valve may be an exhaust valve. Identifying thecylinder valve position includes, for each cylinder, sending lightreflected off the cylinder valve. As elaborated with reference to FIGS.4-5, the laser system may be used to determine valve positions within acylinder, in addition to the position of the piston. Therein, intakevalve opening may be inferred in response to light from the laser systemgetting at least partially blocked from reaching the top of the cylinderpiston. Because the amount of light reflected is reduced compared to theamount of light reflected off of the top surface of the piston whenemitted pulses are not blocked, the controller may account for suchdifferences and use the information to determine that the givencylinder's intake valve is open. Based on the order of valve operationswithin the drive cycle, the controller may also infer that thecylinder's exhaust valve is closed. In alternate examples, a drop in theamount of light reflected off the piston surface during laser operationduring an exhaust stroke may be used to infer exhaust valve opening (andintake valve closing).

In embodiments where the intake valve and/or exhaust valve are coupledto respective cams, the illumination measurement data may also be usedto infer the position of cams and camshaft(s) coupled to the valves. Forexample, for each cylinder, the controller may sense light reflected offthe cylinder and estimate the cylinder's intake cam position based on atime elapsed between the operating of the laser ignition device and thesensing of the light.

At 818, the routine includes determining a crankshaft position for theengine based on the piston position measurement performed in eachcylinder at 814. Likewise, at 820, the routine includes determining acamshaft position for the engine based on the cylinder valve (intake orexhaust valve) or cam (intake or exhaust cam) measurement performed foreach cylinder at 816. From 818, the routine proceeds to each of 822,832, and 842 to indicate degradation of an engine crankshaft based onthe piston position of each cylinder (at 822), to indicate degradationof an engine camshaft based on the valve position of each cylinder (at832), and/or to indicate misalignment of a crankshaft relative to acamshaft based on the piston and valve position measurements.

Specifically, at 822, the routine includes comparing the relativeposition of pistons between the engine cylinders (as determined at 818).For example, the piston position of a first cylinder may be determinedand used to estimate the piston position of the remaining enginecylinders (e.g., based on their firing order and engine configuration).

As such, the relative position may be captured statically (as depicted)or dynamically. For example, if the laser is operated in the low energymode while the engine is moving, light from the laser system may bereflected off the top of a cylinder piston, and the reflected light willhave a different frequency relative to the initial light emitted. Thisdetectable frequency shift is known as the Doppler Effect and has aknown relation to the velocity of the piston if the piston is moving.Thus, the illumination measurement may be used to determine the positionand velocity of the piston. In addition to using the positionalinformation for identifying degradation, the position and velocity ofthe piston may also be used to coordinate the timing of ignition eventsand injection of the air/fuel mixture. For example, position informationmay be used to determine which cylinder fires first an engine restartfrom the idle-stop condition.

At 824, it may be determined if there is a discrepancy between therelative piston position of the cylinders. For example, the expectedposition of the cylinder pistons may be compared to actual estimatedvalues. As such, based on the position of a piston in a given cylinder,the position of pistons in remaining cylinders of the engine may beinferred (e.g., based on cylinder firing order and cylinderconfiguration in the engine). Thus, the relative positions and therelative differences in piston positions may be calculated. If there isa deviation, at 826, crankshaft degradation may be indicated. In oneexample, crankshaft degradation may be indicated based on a differencebetween the piston position of a first cylinder relative to a secondcylinder being higher than a threshold amount. Indicating degradationmay include, for example, setting a diagnostic code to indicate that thecrankshaft is twisted. In an alternate example, the controller may set adiagnostic code to indicate that the crankshaft is broken. In furtherexamples, crankshaft degradation due to a twisted crankshaft may bedifferentiated from crankshaft degradation due to a broken crankshaft.As an example, if the crankshaft was broken, the position of at leastsome of the cylinders may not change. In comparison, if the crankshaftwas twisted, all the cylinders would still be in motion but anunexpected offset may be observed between the timing/position of all thecylinders. If crankshaft degradation is not determined, the routine mayend.

It will be appreciated that while the routine of FIG. 8 depicts thevehicle being in a non-combusting mode, this may not be a limitingcondition. In some embodiments of the routine of FIG. 8, the variousposition-based diagnostic routines may be initiated while the vehicle isin a combusting mode. For example, crankshaft diagnostics may beperformed while the engine is combusting so that the engine can beturned as part of the diagnostic routine so as to better differentiate atwisted crankshaft from a broken crankshaft.

At 832, the routine includes comparing the relative position of valvesbetween the engine cylinders (as determined at 820). Since the cam(e.g., intake cam) position of each cylinder directly correlates withthe corresponding valve (e.g., intake valve) position of each cylinder,the routine may additionally compare the relative cam position of thecylinders (as determined at 816). For example, the intake valve orintake cam position of a first cylinder may be determined and used toestimate the intake valve or intake cam position of the remaining enginecylinders (e.g., based on their firing order, engine configuration, andcylinder stroke). As such, the relative position may be capturedstatically or dynamically, as discussed above. In addition to using thepositional information for identifying degradation, the valve or camposition measurement may also be used to coordinate the timing ofignition events and injection of the air/fuel mixture. For example,position information may be used to determine which cylinder fires firstand which cylinder fuels first. For example, a cylinder with an intakevalve open may be determined to be in an intake stroke and may receivefuel during an engine restart from the idle-stop condition.

At 834, it may be determined if there is a discrepancy between therelative cam or valve position of the cylinders. For example, theexpected position of the cylinder valves or cams may be compared toactual estimated values. As such, based on the position of an intakevalve in a given cylinder, the position of intake valves in remainingcylinders of the engine, as well as the position of exhaust valves inall the cylinders of the engine, may be inferred (e.g., based oncylinder firing order and cylinder configuration in the engine). Thus,the relative positions and the relative differences in valve or cam maybe calculated. If there is a deviation, at 836, camshaft degradation maybe indicated. In one example, camshaft degradation may be indicatedbased on a difference between the valve position of a first cylinderrelative to a second cylinder being higher than a threshold amount. Inanother example, where the valves are independently actuated, it may bedetermined if the measured valve position of a given cylinder is wherethe valve position is expected to be. For example, it may be determinedif the valve position indicates an open intake valve where thecylinder's intake valve has been actuated open. Alternatively, it may bedetermined if the valve position indicates a closed intake valve wherethe cylinder's intake valve has not been actuated open. Indicatingdegradation may include, for example, setting a diagnostic code toindicate that the camshaft is twisted or broken. In an alternateexample, the controller may set a diagnostic code to indicate that anelectric cam system coupled to the camshaft is degraded. In furtherexamples, camshaft degradation due to a twisted camshaft may bedifferentiated from camshaft degradation due to a broken camshaft. As anexample, if the camshaft was broken, at least some of the cylinders mayhave no cam event while others do. In comparison, if the camshaft wastwisted, all the cylinders would have cam events but an unexpectedoffset may be observed between the cam event timing of all thecylinders. In the case of pure actuator systems having no shaft, themeasure intake valve position would be compared to the commanded intakevalve position for each cylinder to identify degradation. If camshaftdegradation is not determined, the routine may end.

It will be appreciated that while the routine of FIG. 8 depicts thevehicle being in a non-combusting mode, this may not be a limitingcondition. In some embodiments of the routine of FIG. 8, the variousposition-based diagnostic routines may be initiated while the vehicle isin a combusting mode. For example, camshaft diagnostics may be performedwhile the engine is combusting so that the engine can be turned as partof the diagnostic routine so as to better differentiate a twistedcamshaft from a broken camshaft.

At 842, the routine includes comparing the relative position of thecrankshaft with the position of the camshaft. As an example, thecrankshaft position determined based on the piston position of the allthe engine cylinders may be compared to the camshaft position determinedbased on the valve position of the engine cylinders. For example, thepiston position for each cylinder, as determined at 814, may be comparedto an intake valve position for the same given cylinder, as determinedat 816. In addition, based on the piston position for the cylinder, acylinder stroke, and thereby, a cylinder valve position may beestimated. The actual and expected values may then be compared. Forexample, the piston position of a first cylinder may be determined usedto estimate the intake valve or intake cam position of the given firstcylinder.

At 844, it may be determined if there is a discrepancy between theestimated valve position and the expected valve position, as determinedbased on the piston position. If there is a deviation, at 846,misalignment of the cylinder crankshaft relative to the camshaft may beindicated. For example, misalignment may be indicated based on adeviation of an estimated cylinder valve position from an expected valveposition, wherein the expected valve position was based on an estimatedpiston position for the same cylinder. Herein, the cylinder valveposition may be a cylinder intake valve position. As discussed above,the cylinder piston position is identified based on a time taken todetect a laser signal, generated at a laser ignition device of theengine, to be reflected off the cylinder piston while the cylinder valveposition is identified based on a time taken to detect a laser signal,generated at the laser ignition device of the engine, to be reflectedoff the cylinder valve.

In another example, misalignment may be indicated based on a differencebetween the estimated crankshaft position and the estimated camshaftposition being higher than a threshold amount. For example, based on themeasured intake valve or intake cam position (e.g., based on the intakevalve/cam, being at a home position) of all the engine cylinders, acamshaft position may be estimated (e.g., a camshaft home position maybe determined). Then, based on the camshaft position, a crankshaftposition correlating with the camshaft position may be determined. Theengine may have a tolerance of up to a threshold amount of change of thecrankshaft from the home position (e.g., up to 4 degrees). If thecrankshaft position is shifted by more than 4 degrees, then misalignmentmay be determined. In response to the discrepancy, the controller mayset a diagnostic code at 846. In response to the indication ofmisalignment, the controller may apply an offset to the cam positionuntil the alignment of the shafts is restored.

In this way, illumination based positional measurements may be used todiagnose an engine camshaft, a cylinder crankshaft, cylinder intakevalves, cylinder exhaust valves, and cylinder intake or exhaust cams.

Now turning to FIG. 9, an example routine 900 is shown for injectorspray pattern diagnostics. In one example, routine 900 may be diagnosticroutine performed as part of the first diagnostic mode (Mode_1), asdescribed at FIG. 6.

At 902, the routine includes confirming that injector diagnostics havebeen selected. For example, it may be confirmed that the engine is inthe first diagnostic mode. Else the routine may end.

In some embodiments, the injector diagnostics may be performed using thelaser system configured as a mobile tool. When in the mobile toolapplication, the routine includes, optionally at 904, installing thelaser and the photodetector (e.g., the CCD camera) in the intakemanifold of the engine. The positioning of the laser and the camera inthe intake manifold may vary depending in whether the fuel injectorbeing diagnosed is a direct fuel injector or a port fuel injector. Forexample, if the spray pattern of a direct fuel injector is beingdiagnosed, the laser and camera may be arranged in-line, such as in thelocation of the spark plug. In comparison, if the spray pattern of aport fuel injector is being diagnosed, the laser and camera may bearranged at an angle to each other, such as with the laser and thecamera in the intake port in the line of the injector spray. It will beappreciated that the laser and the camera may both need to be in theline-of-sight with the injector spray pattern. In one example, thisrequirement may dictate having a second set of low power lasers in theintake ports for port injected engines.

At 906, the routine includes adjusting the output of an electric motorof the hybrid vehicle in which the engine is coupled so as to maintain adefined engine speed-load condition during the diagnostic routine. Forexample, the motor output may be adjusted to maintain a reference enginespeed-load that was used during the last iteration (or all prioriterations) of the injector spray pattern diagnostic routine.

At 908, the routine includes operating the laser ignition device at thelower power level so as to direct laser pulses into the cylinder toplanar sweep the cylinder during an intake stroke of the cylinder withlaser pulses having a power sufficient for cylinder illumination but notsufficient for initiating cylinder combustion. At 910, the routineincludes sweeping the laser in a plane into the path of the fuelinjector spray at defined times since fuel injection by the fuelinjector. For example, the laser may be fired in rapid succession toprovide a planar sweep, or laser arc, across the path of the injectorspray.

At 912, the controller may receive images captured by the photodetector(e.g., the CCD camera) during the laser operation. As such, thephotodetector may have captured images using light generated by thelaser operation in the lower power mode. The images may represent aconic section of the fuel injector spray pattern. Example fuel injectorspray pattern images are shown and discussed with reference to FIG. 10.At 914, the images may be displayed to an operator, such as a servicetechnician or mechanic. In one example, the images may be displayed on adisplay device on the center console of the vehicle. Alternatively, theimages may be displayed on a display device coupled to the mobilediagnostic tool.

At 916, the controller may retrieve and display a reference image of anexpected injector spray pattern. The reference image may beautomatically retrieved and displayed based on the captured image (at912) or based on the selection of the injector diagnostic routine (at902). Alternatively, the reference image may be retrieved upon receivinginput from the vehicle operator, such as via the (touch-interactive)display device. The reference image may include an image of the givenfuel injector previously diagnosed at the given reference enginespeed-load conditions wherein no injector degradation was determined.Alternatively, the reference image may include the image of acorresponding fuel injector (e.g., a similar port or direct fuelinjector) previously diagnosed at the given reference engine speed-loadconditions wherein no injector degradation was determined. In this way,the generated image and the reference image may be presented to thevehicle operator for comparative analysis.

At 918, it may be determined if operator input has been receivedindicating injector degradation. For example, the operator may comparethe generated image with the reference image to see if the injectorspray pattern is as required to be. FIG. 10 shows example injector spraypattern images captured in the laser arc by a photodetector coupled tothe laser system. At 1000, an expected spray pattern is shown.Specifically, 1000 may be a reference image representing a fuel injectorspray pattern captured during the reference engine speed-load conditionswhile the injector was not degraded. In comparison, 1002, shows adegraded injector spray pattern. Since the spray cone at 1002 is notconically shaped (compare to conically shaped spray cone of 1000), andhas part of the conic section missing or skewed, based on the images, anoperator may be determine that the fuel injector is degraded. Forexample, the injector may be determined to be clogged.

If the operator input indicates degradation of the fuel injector, at920, the controller may set a diagnostic code to indicate thedegradation. The controller may also request fuel injector replacement.If no input is received, the controller may indicate at 922 that thefuel injector is not degraded. Optionally, if no degradation isdetermined, the controller may save the image captured during the giveniteration of the fuel injector diagnostic routine in the controller'smemory for use a reference image during a later iteration of thediagnostic routine.

Now turning to FIG. 11, an example routine 1100 for diagnosing cylinderairflow patterns is shown. In one example, routine 1100 may be adiagnostic routine performed as part of the first diagnostic mode(Mode_1), as described at FIG. 6. Furthermore, the diagnostic routinemay be performed using the laser system configured as a mobile tool.

At 1102, the routine includes confirming that airflow diagnostics havebeen selected. For example, it may be confirmed that the engine is inthe first diagnostic mode. Else the routine may end. At 1104, theroutine includes presenting high humidity air into the air intakesystem. For example, a water spray may be injected or introduced intothe air intake system (or directly into the intake manifold). Inalternate examples, instead of high humidity air, smoke may be presentedto the air intake system of the engine.

At 1106, the routine includes operating the laser in the lower powermode. As discussed previously, the laser system is operated to directlaser pulses into the cylinder to planar sweep the cylinder during anintake stroke of the cylinder with laser pulses having a powersufficient for cylinder illumination but not sufficient for initiatingcylinder combustion. At 1108, the routine includes sweeping the laser ina plane into the path of cylinder airflow at defined times since intakevalve opening (IVO). For example, the laser may be fired in rapidsuccession to provide a planar sweep across the cylinder during theintake stroke.

In some examples, a swirl control valve or charge motion control valvein the intake port, upstream of the intake valve, may be operated duringthe introduction of the humid air or smoke so as to accentuate theswirling motion of the airflow received in the cylinder during theintake stroke.

At 1110, the controller may receive images captured by the photodetector(e.g., the CCD camera) during the laser operation. As such, thephotodetector may have captured images using light generated by thelaser operation in the lower power mode. The images may representairflow patterns in the cylinder. Specifically, the camera and laserscan may illuminate the airflow pattern by viewing the water vapor (fromthe high humidity air) condensing in the cylinder as it encounters lowpressure during the intake stroke.

At 1112, the captured images may be displayed to an operator, such as aservice technician or mechanic. In one example, the images may bedisplayed on a display device on the center console of the vehicle.Alternatively, the images may be displayed on a display device coupledto the mobile diagnostic tool.

At 1114, the controller may retrieve and display one or more referenceimages of an expected cylinder airflow pattern. The reference image maybe automatically retrieved and displayed based on the captured image (at1110) or based on the selection of the airflow diagnostic routine (at1102). Alternatively, the reference image may be retrieved uponreceiving input from the vehicle operator, such as via the(touch-interactive) display device. The reference image may include animage of airflow pattern captured previously when no intake valve orairflow degradation was determined. Optionally, the reference image mayhave been captured while operating the engine at a reference enginespeed-load condition, or the same engine speed-load condition at whichthe images were currently captured. As such, in the absence of airflowdegradation (such as due to intake valve degradation), the introducedhumid air or smoke may generate a helical pattern in the cylinder due tothe interaction of the humid air or smoke with the low pressureencountered in the cylinder during the intake stroke. Thus, thereference image may include a helical pattern, such as a swirl orcircle. In this way, the generated image and the reference image may bepresented to the vehicle operator for comparative analysis.

At 1116, it may be determined if operator input has been receivedindicating airflow degradation. For example, the operator may comparethe generated image with the reference image to see if the airflowpattern is helical, as required to be. If the captured image depictsturbulence in random parts of the cylinder, the operator may infer andindicate that airflow in the cylinder is degraded. If the operator inputindicates degradation of cylinder airflow, at 1118, the controller mayset a diagnostic code to indicate the degradation of airflow due topossible degradation of the intake valve. For example, the controllermay indicate that there is potential build-up of material on the intakevalve. Alternatively, the controller may indicate that the swirl controlvalve is degraded. The controller may accordingly request controlactions be performed, such as advancing the intake cam timing tocompensate for the degraded flow through the valve. If no input isreceived, the controller may indicate at 1120 that the airflow (andtherefore the intake valve) is not degraded. Optionally, if nodegradation is determined, the controller may save the image capturedduring the given iteration of the airflow diagnostic routine in thecontroller's memory for use a reference image during a later iterationof the diagnostic routine.

Now turning to FIG. 12, an example routine 1200 for diagnosing coolantleakage into a cylinder is shown. In one example, routine 1200 may be adiagnostic routine performed as part of the first diagnostic mode(Mode_1), as described at FIG. 6. Furthermore, the diagnostic routinemay be performed using the laser system configured as a mobile tool.

At 1202, the routine includes confirming that coolant flow diagnosticshave been selected. For example, it may be confirmed that the engine isin the first diagnostic mode. Else the routine may end. At 1204, theroutine includes operating the laser in the lower power mode. Asdiscussed previously, the laser system is operated to direct laserpulses into the cylinder having a power sufficient for cylinderillumination but not sufficient for initiating cylinder combustion. At1206, the routine includes using the laser pulses to planar sweep thecylinder during an intake stroke of the cylinder. Additionally, at 1206,the routine includes operating the laser in the lower power mode toplanar sweep the cylinder again, after cylinder combustion, during anexhaust stroke of the given cycle of the cylinder. For example, thelaser may be swept into the cylinder at defined times since intake valveopening (IVO) and before exhaust valve closing (EVC). For example, thelaser may be fired in rapid succession to provide a planar sweep acrossthe cylinder during the intake stroke and the exhaust stroke.

At 1208, the controller may receive images captured by the photodetector(e.g., the CCD camera) during the laser operation. As such, thephotodetector may have captured images using light generated by thelaser operation in the lower power mode. The images captured in theintake stroke may represent presence or absence of coolant entry intothe cylinder during the intake stroke following an intake valve openingevent. The images captured in the exhaust stroke may represent presenceor absence of white smoke in the exhaust of the cylinder followingcombustion of any leaked coolant.

At 1210, the captured images may be displayed to an operator, such as aservice technician or mechanic. In one example, the images may bedisplayed on a display device on the center console of the vehicle.Alternatively, the images may be displayed on a display device coupledto the mobile diagnostic tool.

At 1212, the controller may retrieve and display one or more referenceimages of an expected cylinder airflow pattern. The reference image maybe automatically retrieved and displayed based on the captured image (at1208) or based on the selection of the coolant flow diagnostic routine(at 1202). Alternatively, the reference image may be retrieved uponreceiving input from the vehicle operator, such as via the(touch-interactive) display device. The reference image may include animage of expected coolant flow and exhaust smoke generation capturedpreviously when no coolant leakage into the given cylinder wasdetermined. Optionally, the reference image may have been captured whileoperating the engine at a reference engine speed-load condition, or thesame engine speed-load condition at which the images were currentlycaptured. As such, in the presence of coolant entry, coolant flow orvapors may be seen entering the cylinder from the bottom of the pistonduring the intake stroke. The coolant may then be seen generating excesswhite smoke in the exhaust stroke, due to combustion of the coolantduring the cylinder combustion event. In this way, the generated imageand the reference image may be presented to the vehicle operator forcomparative analysis.

At 1214, it may be determined if operator input has been receivedindicating coolant entry. For example, the operator may compare thegenerated image with the reference image to see if coolant has leakedinto the cylinder. If the operator input indicates degradation ofcylinder airflow, at 1216, the controller may set a diagnostic code toindicate the degradation of coolant flow and leakage of coolant into thecylinder due to possible degradation of the piston rings. If no input isreceived, the controller may indicate at 1218 that the coolant flow (andtherefore the cylinder piston ring) is not degraded. Optionally, if nodegradation is determined, the controller may save the image capturedduring the given iteration of the coolant flow diagnostic routine in thecontroller's memory for use a reference image during a later iterationof the diagnostic routine.

Now turning to FIG. 13, an example routine 1300 for diagnosing aconverging lens coupled to the laser system of a cylinder is shown. Inone example, routine 1300 may be a diagnostic routine performed as partof the second diagnostic mode (Mode_2), as described at FIG. 7.Furthermore, the diagnostic routine may be performed using the lasersystem configured as a mobile tool.

At 1302, the routine includes confirming that lens diagnostics have beenselected. For example, it may be confirmed that the engine is in thesecond diagnostic mode. Else the routine may end. At 1304, the routineincludes operating the laser in the higher power mode. As discussedpreviously, the laser system is operated to direct laser pulses into thecylinder having a sufficient for initiating cylinder combustion and morepower than required only for cylinder illumination. The laser pulses mayalso be used to planar sweep the cylinder during a compression stroke ofthe cylinder.

At 1306, the controller may capture in-cylinder images, via thephotodetector of the laser system, using light generated during cylindercombustion. At 1308, the controller may receive images captured by thephotodetector (e.g., the CCD camera) during the laser operation. Assuch, the photodetector may have captured images using light generatedduring cylinder combustion. The images may represent the flame frontduring the cylinder combustion event. At 1308, the captured images maybe displayed to an operator, such as a service technician or mechanic.In one example, the images may be displayed on a display device on thecenter console of the vehicle. Alternatively, the images may bedisplayed on a display device coupled to the mobile diagnostic tool.

At 1310, based on the captured images, a location of flame initiationmay be determined. For example, based on the intensity of the capturedimages, a location on the piston surface or cylinder wall where theflame front initiated may be determined. As such, since the flame isinitiated via laser ignition, and further since the laser system uses aconverging lens to direct the laser pulse into the cylinder forcombustion initiation, the location of flame initiation may alsocorrelate with the focal point of the lens. Thus, based on the receivedimage, the controller may determine the focal point of the lens coupledto the laser system.

At 1312, the controller may retrieve and display one or more referenceimages of an expected flame front initiation and progression. Thereference image may be automatically retrieved and displayed based onthe captured image (at 1306) or based on the selection of the lensdiagnostic routine (at 1302). Alternatively, the reference image may beretrieved upon receiving input from the vehicle operator, such as viathe (touch-interactive) display device. The reference image may includean image of expected flame front initiation and progression. Optionally,the reference image may have been captured while operating the engine ata reference engine speed-load condition, or the same engine speed-loadcondition at which the images were currently captured. As such, if thelens is misaligned, the location of flame initiation may be skewed to aside, and may not correlate with the expected location of flameinitiation. Thus, the generated image and the reference image may bepresented to the vehicle operator for comparative analysis.

At 1314, it may be determined if operator input has been receivedindicating lens misalignment or incorrect location of flame initiation.For example, the operator may compare the generated image with thereference image to see if the flame initiated towards an edge of thecylinder. If the operator input indicates degradation of flameinitiation, at 1316, the controller may set a diagnostic code toindicate the degradation of flame initiation due to possiblemisalignment of the laser system lens. The controller may furtherindicate that lens adjustment (e.g., realignment) is required. If noinput is received, the controller may indicate at 1318 that the flameinitiation, and lens arrangement is not degraded. Optionally, if nodegradation is determined, the controller may save the image capturedduring the given iteration of the lens diagnostic routine in thecontroller's memory for use a reference image during a later iterationof the diagnostic routine.

It will be appreciated that in still further examples, one or more ofthe above described routines may be adjusted to keep the lens of thelaser ignition system clean. As an example, the camera lens may belocated relatively high on the side of the cylinder where the pistonring may clean the lens. Additionally, the laser could burn off residualsoot. As such, this approach may require either a shutter or may need adirect line of laser signt blocked to avoid damaging the photodetector(such as the CCD camera).

As another example, the camera (or photodetector) and the laser may beconfigured to share a lens. Therein, regular laser operation may burnoff anything covering the lens, thereby cleaning the lens during laseroperation.

In this way, a laser ignition system may be advantageously used todiagnose various cylinder components and conditions. By using the laserto illuminate the cylinder and the photodetector to capture in-cylinderimages using laser illumination, a visual inspection of the cylinder canbe performed without the need for bore-scopes, engine tear down, orother labor, cost, and time-intensive approaches. By enabling a mechanicto see the images of the interior of the cylinder, along with relevantreference images of the same cylinder, the engine health may bediagnosed more accurately and reliably by the mechanic. By usingexisting engine hardware to perform the visual inspection, component andcost reduction benefits are achieved. Overall, engine inspection can besimplified without reducing inspection accuracy.

Note that the example control and estimation routines included hereincan be used with various engine and/or vehicle system configurations.The control methods and routines disclosed herein may be stored asexecutable instructions in non-transitory memory. The specific routinesdescribed herein may represent one or more of any number of processingstrategies such as event-driven, interrupt-driven, multi-tasking,multi-threading, and the like. As such, various actions, operations,and/or functions illustrated may be performed in the sequenceillustrated, in parallel, or in some cases omitted. Likewise, the orderof processing is not necessarily required to achieve the features andadvantages of the example embodiments described herein, but is providedfor ease of illustration and description. One or more of the illustratedactions, operations and/or functions may be repeatedly performeddepending on the particular strategy being used. Further, the describedactions, operations and/or functions may graphically represent code tobe programmed into non-transitory memory of the computer readablestorage medium in the engine control system.

It will be appreciated that the configurations and routines disclosedherein are exemplary in nature, and that these specific embodiments arenot to be considered in a limiting sense, because numerous variationsare possible. For example, the above technology can be applied to V-6,I-4, I-6, V-12, opposed 4, and other engine types. The subject matter ofthe present disclosure includes all novel and non-obvious combinationsand sub-combinations of the various systems and configurations, andother features, functions, and/or properties disclosed herein.

The following claims particularly point out certain combinations andsub-combinations regarded as novel and non-obvious. These claims mayrefer to “an” element or “a first” element or the equivalent thereof.Such claims should be understood to include incorporation of one or moresuch elements, neither requiring nor excluding two or more suchelements. Other combinations and sub-combinations of the disclosedfeatures, functions, elements, and/or properties may be claimed throughamendment of the present claims or through presentation of new claims inthis or a related application. Such claims, whether broader, narrower,equal, or different in scope to the original claims, also are regardedas included within the subject matter of the present disclosure.

The invention claimed is:
 1. A vehicle engine method, comprising:initiating cylinder combustion by operating a laser ignition device at apower higher than a threshold power required for only illuminating acylinder; generating an in-cylinder image after operating the laserignition device using light generated via the cylinder combustion;displaying the generated image and a reference image to an operator on avehicle display device; and based on operator input, indicatingdegradation of a cylinder component.
 2. The method of claim 1, furthercomprising, comparing the generated image to the reference image; andbased on the comparing, indicating degradation of the cylindercomponent.
 3. The method of claim 1, wherein the reference image is areference image of the cylinder component, the reference image selectedbased on the generated image.
 4. The method of claim 1, whereinoperating the laser ignition device at higher power includes directinglaser pulses into the cylinder to planar sweep the cylinder during acompression stroke of the cylinder.
 5. The method of claim 4, whereinthe generated image is generated at a photodetector coupled to the laserignition device, and wherein the reference image includes a referenceimage previously generated by the photodetector.
 6. The method of claim1, wherein indicating degradation includes setting a diagnostic code. 7.The method of claim 1, wherein the cylinder component is a piston,wherein the generated image is indicative of a piston head, and whereinindicating degradation includes indicating piston head melting.
 8. Themethod of claim 1, wherein the generated image is indicative ofpropagation of a cylinder combustion flame, and wherein indicatingdegradation includes indicating incorrect flame propagation.
 9. Themethod of claim 1, wherein the cylinder component diagnosed is the laserignition device, wherein the generated image is indicative of anorientation of laser output by the laser ignition device, and whereinindicating degradation includes indicating incorrect orientation of thelaser output.
 10. The method of claim 1, wherein the cylinder componentdiagnosed is a lens coupled to the laser ignition device, wherein thegenerated image is indicative of a focal point of the lens, and whereinindicating degradation includes indicating incorrect flame initiation.11. A method for an engine, comprising: operating a laser ignitiondevice during a compression stroke to initiate cylinder combustion;transmitting an in-cylinder image generated after operating the laserignition device to a vehicle display device, the image generated by aphotodetector of a cylinder using light generated via the cylindercombustion; and based on input received from an operator, setting adiagnostic code indicating degradation.
 12. The method of claim 11,wherein the photodetector is coupled to the cylinder, the photodetectorincluding a lens and a camera.
 13. The method of claim 12, wherein thein-cylinder image is an image of a cylinder component or combustionparameter, the method further comprising displaying a reference image tothe operator on the vehicle display device, the reference image selectedbased the cylinder component or combustion parameter.
 14. The method ofclaim 13, wherein indicating degradation includes indicating degradationof the cylinder component or combustion parameter being diagnosed. 15.The method of claim 14, wherein the in-cylinder image is an image ofcombustion flame initiation, and wherein indicating degradation includesindicating degradation of the photodetector lens.
 16. A hybrid vehiclesystem comprising: an engine including a cylinder; an electric motor; adisplay device in a cabin of a vehicle; a laser ignition system coupledto a cylinder head and configured to direct light pulses into thecylinder; a photodetection system coupled to the laser ignition systemand the cylinder for generating images of an inside of the cylinderusing the light pulses from the laser ignition system; and a controllerwith non-transitory memory and computer readable instructions for:operating the laser ignition system during a compression stroke toinitiate cylinder combustion; displaying an in-cylinder image generatedat the photodetection system following the operating to a vehicleoperator on the display device; displaying a reference image retrievedfrom the controller's memory on the display device, the reference imagebased on the generated in-cylinder image; and indicating cylindercombustion degradation based on operator input received following thedisplaying.
 17. The system of claim 16, wherein the photodetectionsystem includes a CCD camera with a fish-eye lens, and wherein thedisplaying includes wirelessly transmitting images within the vehiclesystem from the photodetection system to the display device.
 18. Thesystem of claim 17, wherein the controller includes further instructionsfor: adjusting an output of the electric motor when operating the laserignition system to maintain a defined engine speed and load whilegenerating the in-cylinder image.
 19. The system of claim 18, whereinoperating during the compression stroke includes operating the laserignition system above a threshold power level.